CT90 Restoration Adventures

More Honda CT90 & CT200 3D Printed Parts - Hard to Find K1 Parts and Others

2021-07-02T10:49:00.000-07:00

I'm continuing to find and endless number of opportunities to utilize my 3D printer to make useful parts for my CT90 project bikes, my fishing float tube, and other hobbies that I have. I thought I would share a few of the latest CT90 parts that I have designed/modeled and printed.

All of the designs I share below, I first modeled using my ViaCad 2D/3D modeling program.

More 3D Printed Honda CT90 Part Designs

3D Printed CT90 K1 Rear Airbox Snorkel

CT90 K1 3D Printed Carb to Air Filter Boot

A 3D Printed Valve Spring Compression Tool

CT90 K1 Front Fork Cover Side Reflector Base

On almost every older CT90 I work on (I guess they are all old...) the little rubber caps on that cover and help hold in the bulbs on the base of the speedo are cracked, disintegrating before my eyes or are just missing.

I modeled up both a short cap that has a hole for one wire and a taller cap that has a slot in its base that allows two wires to pass through as shown in the pictures below.

When I modeled the reflector base I took into account the taper of the fork cover and added a small raised dot for the end of the reflector base that should point up. The 3D printed part is on the left in the picture above and the stock Honda part is on the right.

I printed these reflector bases using SainSmart TPU and PETG and I think that both materials work well for this application.

Here is the link to the .stl files at Thingiverse for the reflector base.

Here is the link to the .stl files at Prusaprints for the reflector base.

CT90 K1 Upper Triple Tree Turn Signal Mounting Hole Plugs

Someone had asked after I did an earlier post on plugs I had made for the rear fender for the turn signal holes if I could make plugs for the turn signal mounting holes in the CT90 K1 upper triple tree, so I did and here they are. That are similar to the original plugs and will functionally fill the holes.

I made the design of the features that fit into the holes slightly different than the original Honda plug designs as I printed these parts using SainSmart TPU which is significantly stiffer, but again still functional.

I have included links to .stl files below, but if you don't have a 3d printer I also sell a set of these plugs on eBay here at this link.

Here is the link to the .stl files at Thingiverse for the plug.

Here is the link to the .stl file at Prusaprints for the plug.

CT200 and CT90 K0 & K1 Battery Compartment Bumper

I've noticed on some of my older K0 & K1 CT90's and also on my CT200's that they have a round bumper on the back wall of the battery compartment. I still had one of these rubber bumpers so I decided to create a model of the part so that I could print copies on my 3D printer.

Here is a shot of the original bumper.

Here is a shot of the part I modeled and then printed next to the original rubber bumper.

Here is the 3D printed bumper printed in TPU installed is a CT200 frame

Because the TPU is not near as stretchy as rubber, it is a little tough pulling the stub of the bumper through the hole in the frame, but with a little grease, twisting and the help of a small screwdriver, the bumper was installed. Using a lower durometer filament would make this part easier to install.

Here is the link to the .stl file at Thingiverse

Here is the link to the .stl file at Prusaprinters

CT90 K1 Front Fender Reflector Holder - A Work in Progress

I've been working off and on on this part as I have been finding it difficult to come up with a model of this part that prints well.

In the picture below the stock reflector holder with the metal band is on the left and the three on the right are different 3D printed designs I have tried with varying degrees of success. The two right most designs are made from PETG and have a split on the lower edge to allow for installation of the reflector. The one 3D printed design in the lower center with the reflector installed is made from TPU and the reflector snaps into place.

In the end I think I will have a design that is almost identical to the stock part in that it will accept the metal band that wraps around the stock reflector holder. I also think I will have an all plastic design out of TPU or PETG that won't use the metal band.

I'll update this post in the future when I get a final design I like figured out.

I hope you found this information useful.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

A new Batch of Honda CT90 and CT200 3D Printed Parts

2021-04-17T17:53:00.002-07:00

I'm continuing to find and endless number of opportunities to utilize my 3D printer to make useful parts for my also endless number of CT90 project bikes that I am working on, so I thought I would share a few of the latest CT90 parts that I have designed and printed.

All of the designs I share below, I first modeled using my ViaCad 2D/3D modeling program.

Related Posts:

More 3D Printed Honda CT90 Part Designs

3D Printed CT90 K1 Rear Airbox Snorkel

CT90 K1 3D Printed Carb to Air Filter Boot

A 3D Printed Valve Spring Compression Tool

Speedo Light Bulb Socket Caps

I modeled up both a short cap that has a hole for one wire and a taller cap that has a slot in its base that allows two wires to pass through as shown in the pictures below.

I have used these caps on speedo's from a K1 and a K3 and they should work on several other models. I haven't checked them out yet on a speedo from a K0 or a CT200 but will do so soon. Some later model CT90's and I assume CT110's have a bayonet mount that takes a larger diameter cap that I plan on modeling in the future.

I printed these caps using SainSmart TPU which is a nice flexible material, but significantly stiffer than the original rubber used for these parts.

Here is the link to the .stl files at Thingiverse for both the short and tall caps.

Here is the link to the .stl files at Prusaprints for both the short and tall caps.

CT90 Rear Fender Plugs

Another part that seems to be missing or in really poor shape on most bikes I pick up are the rubber plugs that go in the holes in the rear fender that support the addition of turn signals.

I modeled up both smaller round plug and the longer plug designed to three holes. I made the design of the features that fit into the holes slightly different than the original Honda plug designs as I printed these parts using SainSmart TPU which is significantly stiffer.

I have included links to .stl files below, but if you don't have a 3d printer I also sell a set of these plugs on eBay here at this link.

Here is the link to the .stl files at Thingiverse for both the long and round plugs.

Here is the link to the .stl file at Prusaprints for both the long and round plugs.

CT90 K1 Down Tube Support Bracket

It seems like a lot of the basket case CT90's I find are K1's which are kind of an odd duck in that many of the parts on this model CT90 are not common to any other models.

One part that can be hard to find if it is missing is the metal bracket that holds down the front end of the air filter housing and also provides the mount for the lower left side of the down tube cover.

I modeled up a working part and while its not as elegant as I would like the design, it is completely functional.

The bracket is designed with a small cavity at the end that you insert a standard 6mm nut into and that provides the threads for screw that is used to hold the lower end of the down tube cover.

I printed this part in PTEG which seems more than adequate for the application. You'll also find an alternate design of this bracket that provides more clearance for the upper engine mount bolt.

Here is the link to the .stl file at Thingiverse

Here is the link to the .stl file at Prusaprinters

CT90 K1 Speedo Housing Gasket

The other part I modeled for the CT90 K1 was the gasket that goes between the speedo and the headlight housing. You can find this gasket readily available on-line at the normal sources, but I had an itch and decided to model and print it up for one of the K1's I am currently rebuilding.

I also printed this part in SainSmart TPU.

Here is the link to the .stl file at Thingiverse

Here is the link to the .stl file at Prusaprinters

CT200 Air Filter Housing Gasket

The last part I will share is a gasket that is used on a CT200 between the air filter housing and the frame.

This is one of the simplest parts I have modeled and I also printed this using SainSmart TPU.

Here is the link to the .stl file at Thingiverse

Here is the link to the .stl file at Prusaprinters

I hope you found this information useful.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

More 3D Printed Honda CT90 Part Designs

2021-03-19T22:24:00.001-07:00

I've been having fun modeling a number of Honda CT90 parts and then printing them on my printer. and I thought I would share them here along with links to .stl files in case others wanted print parts for their own individual use.

To create all of the parts I share below, I first created a 3D model in my ViaCad 2D/3D modeling program.

Ignition Switch Access Hole Plug

The first part I will share is my design for the rubber plug that goes in the hole where the wires from the ignition switch exit.

I have printed this plug using SainSmart TPU filament which is flexible enough so the plug can be installed, but it is not near as flexible as a new stock rubber plug, but much more flexible than a 50 year old rock hard stock rubber plug.

Here is the link to the .stl file at Thingiverse for the ignition hole plug.

Here is the link to the .stl file at PrusaPrinters for the ignition hole plug.

Spare Gas Tank Helmet Lock Cover

The next part is the little cover that goes on the helmet lock on the spare gas tank bracket. Here are a couple of pictures of the cover and these were all printed using PTEG.

Here is a picture of the 3D printed cover next to a stock cover.

Here is a link to the .stl file at Thingiverse for the cover shown above.

Here is a link to the .stl file at PrusaPrinters for the cover shown above

Replacement Skirts for K0 & K1 Steering Stem Nuts

The last two parts are the skirts that go on the steering stem nut on both the K0 and K1 versions of the CT90.

I have printed these skirts in both SainSmart TPU and PETG. I like the flexible chemical resistance of TPU and it also makes makes installing the skirts easier on the steering stem nut, but the PETG is closer to the hard plastic of the stock skirt, but does require more force when installing to overcome the detent feature I added on the skirt to secure it to the groove in the nut.

Here is a picture of the TPU printed skirt for a K1 next to the skirts from a stock Honda K1 CT90 steering stem nut.

Here is the link to the .stl file at Thingiverse for the skirt for the CT90 K1 steering stem nut.

Here is the link to the .stl file at PrusaPrinters for the skirt for the CT90 K1 steering stem nut.

The skirt on the K0 steering stem nut is very similar to the the K1, except the skirt is longer.

Here is the link to the .stl file at Thingiverse for the skirt for the CT90 K0 steering stem nut.

Here is a link to the .stl file at PrusaPrinters for the skirt for the CT90 K0 steering stem nut.

I hope you found this interesting and maybe this will spark a few similar designs from others who have 3D printers.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

A 3D Printed CT90 Valve Spring Compression Tool

2021-02-18T20:51:00.003-08:00

Since I picked up a 3D printer this Christmas, I've really found that it's a great tool, especially if you have a good 3D modeling program on your computer and reasonable skills to be able to design the part you would like to print.

For a limited time I am including for free one of my prototype valve spring compression tools that I describe below with the purchase of my clutch holding tool available here at this link.

My fundamental problem has been that I keep coming up with new designs I would like to print and get them 90% complete, before I get another idea and I'm off on another tangent (such is the life of a retired guy...). One of those designs is a Valve Spring Compression tool to use on a Honda CT90.

I've been using a C-Clamp and simple piece of tubing as my valve spring compression tool up until now and it always works and gets the job done. I've done a post here at my blog on the C-Clamp tool here at this link.

I had an idea and used my ViaCad 2D/3D to model the two parts below that make up the valve spring compressor design.

The idea behind the design is that the rightmost part in the picture above acts like a rocker arm and is rotated when a cam profile on the lift part is rotated by the integral lever on that part.

I went through a number of different configurations of the designs until I found one that worked just right. The challenge with the design is that you have to create enough travel to compress the spring far enough so the keepers can be removed, but the have the right profile so that when the pressure is released off the spring that it doesn't clamp the tool in the head to where it can't be removed.

In the end I arrived at the design which consists of the two parts shown in the picture below.

I also made a short video at the link below to show how the tool actually works in use.

As I show in the video, the part isn't 100% ready for prime time. The design works just fine, but I have had a failure or two after 10 or 15 uses, so it isn't as robust as I would like. Durability isn't really an issue with a 3D printed tool like this if you have your own printer as you can just print a new tool.

I plan on looking at changing some of the internal printing settings to increase the percent fill or add additional solid layers throughout the design. The current parts I have printed have been made with PETG and I may look at picking up a spool of nylon filament to see if I can get a significant increase in strength.

I'll try and update this post when I get to a final design/material configuration, but I think I'm 90 to 95% of the way there.

I hope you found this interesting and maybe this will spark a few similar designs from others who have 3D printers.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

3D Printed CT90 K1 Rear Airbox Snorkel

2021-01-30T22:37:00.005-08:00

One of the other parts I recently modeled and made a 3D print of is the rubber Snorkel/boot that attaches to the rear of the 1969 K1 CT90's airbox, and that resides in the battery compartment area in the frame when the airbox is installed.

Here is a picture of the model I made in ViaCad 2D/3D.

The following are a couple of photos of the snorkel that I printed using a flexible TPU filament next to the stock rubber snorkel that I removed from the airbox.

The 3D printed snorkel has a nice snow fit when it is mounted to the cylindrical feature on the airbox.

At some point I plan on uploading .stl files for my snorkel design to Thingiverse.com and also the Prusa 3D parts library, so others can print the snorkel. Once I do up load the file, I'll add a link to this post.

I hope you found this information useful!

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

CT90 K1 3D Printed Carb to Air Filter Boot

2021-01-16T21:22:00.002-08:00

I recently picked up my first 3D printer and now have an endless list of things I plan on making on the printer for my CT90's and other hobbies that I have.

The 3D printer I picketed up is a Prusa i3 MK3S+ and I purchased it during a Black Friday sale Prusa had run last year. I purchased the printer as a kit and it was a fun project in itself, but since I got the printer up and running, I've found it to be very capable and I am happy with my printer choice.

One of my first projects was to design and print the a replacement for the rubber boot that goes between the carb and air filter on the 1969 CT90 K1. I've owned sever K1's and I think I had only one where the boot hadn't fully degraded and wasn't falling apart like the one in the picture below.

There are replacement boot/filter holders available, but they are almost $70.00 which is pretty pricey. Most of the time the filter holder portion of the assembly is just fine and its just the rubber portion that has fallen apart.

To design the boot I used ViaCAD 2D/3D ,Version 11, and this is the design I ended up with that fits the standard 4 screw carb on the early K1's. The diameter of the open that mates to the carb is just under 36mm which provides a nice snug fit on the carb.

I designed my boot to be 3D printed using TPU which is a flexible filament. I also included an internal groove on the end that mates and snaps over the rimed feature on the filter holder that would normally accept the rubber boot.

Here is the link to the .stl file at Thingiverse for the boot to use with the stock 4 screw carb.

Here is the link to the .stl file at PrusaPrinters for the boot to use with the stock 4 screw carb.

I also designed a second boot that has an opening that is just under 32mm to fit later 2 screw carbs that are easier to find and can be used on the K1 if you use a later version intake manifold. The picture below is of that design.

Here is the link to the .stl file at Thingiverse for the boot to use with the a newer 2 screw carb.

Here is the link to the .stl file at PrusaPrinters for the boot to use with the newer 2 screw carb.

I have printed up both of the above designs in a SainSmart TPU and fit them on the filter holder and on each of the two sizes of carbs and everything looks good. I've also been able to do a trial fit with the 4 screw version on a bike and it fit up just fine.

Here are a few pictures of the completed boots that I printed.

Here are a couple of pictures of one of the boots connected to the filter holder. The snap fit works well, but is on the snug side, so while you can snap it on by hand (with a little work) you need a screw driver or something similar to help pry it off of the lip of the feature on the filter holder it snaps on too.

And here is a picture or two of the assembly slid into the filter housing.

I don't know how well the TPU will hold up over time, but it does have some gas and oil resistance.

The TPU is flexible enough for the application, but isn't elastic like rubber. I also used a fairly heavy wall thickness to make the part robust, but now that I have printed the parts I probably could have gone with a thinner wall which would have made the boots that much more flexible. Now that I have the model, it will be easy to try other more flexible and elastic materials in the future that may also be more durable and fuel resistant.

My plan is to develop models for all the CT200 and CT90 rubber boot applications, so I can print the parts I need on future builds. I build bikes to get them running and to ride, so I'm more interested in having a functional part and can live with the shame of not having a concourse correct bike.

As I develop future CT200/CT90 3D parts I'll be uploading those .stl files also.

I hope you found this information useful!

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Aftermarket Honda CT90 Carburetor Drain Modification

2020-06-21T23:18:00.001-07:00

Relocating the Drain on a Aftermarket Honda CT90 Carburetor

I recently picked up an aftermarket carb for one of my CT90's off of eBay that is very similar in design to a Klein 556A carburetor except for one detail and that was the orientation of the drain fitting. The drain fitting pointed straight down verses straight back and is a common issue with aftermarket CT90 carbs.

Here is a picture with the old carb on the left and the new carb on the right.

I purchased the carb off of eBay instead of fixing the old carb because it was only $28.00 and I always wanted to try one of these carbs out. I thought this one which I purchased from eBay seller Carbstar, was a deal as most of the aftermarket carbs with the correct choke lever configuration were always in the $50.00 range.

The only real issue with the new carb was that the drain was pointed down instead of to the rear like a stock CT90 carb, so I decided to modify the carb to relocate the drain to the correct location.

I knew that the fuel line and drain fittings were pressed and or shrink fit into the carb body, so I figured I should be able to remove the drain fitting by pulling it out.

Pulling out the drain fitting wasn't going to be easy, but the way I decided to approach removing it was using a pair of pliers and a small square of heavy gauge vinyl to try and protect the brass drain fitting.

To really be able to pull on the fitting I removed the lower bowl of the new carb and secured it in the wood working vise on my bench as shown below.

My technique was to pull had and apply a very slight wiggling motion to the drain fitting. The drain fitting is brass so I minimized the wiggling to avoid breaking it and with a little bit of work it finally came out.

The next step was to drill the new hole at the rear location. I measured the old hole and figured that a 5/32" bit would give me a hole that was a few thousandths smaller than the diameter of the drain fitting, so I would end up with an interference fit. The first step in drilling the new hole was to remove the actual drain nob from the bowl and then use a center punch at the location I wanted to drill my hole.

I next drilled and then chamfered the hole.

I next blew out all the passages with air to make sure all the chips were gone and then I was ready to install the drain fitting in the hole I just drilled.

Before I installed the drain fitting I put it in my freezer for about a half an hour so that it would cool down and shrink ever so slightly to make the installation easier. To install the drain fitting in the new hole I just use a plastic mallet to tap it into place so there was about a 1/4" of engagement which is about the same as when the fitting was installed in the previous location.

With the drain fitting installed in the new location I now needed to deal with the old hole. To plug the old hole I made up a small aluminum plug like shown in the picture below that was a few thousandths

larger in diameter than the hole and then I tapped it into place.

With the plug installed I reassembled the bowl back onto the carb and now the new carb had the same drain configuration as the stock carb.

With the carb modified, I bolted it up on the CT90 the old carb came off of and it worked like a champ and I am very happy I picked up this carb as $28.00 is only a little bit more than a rebuild kit and the modification to relocate the drain is not really all that difficult.

I hope you found this information useful!

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Honda CT90 and CT200 Gas Cap Teardown

2020-06-20T10:39:00.003-07:00

Honda CT90 and CT200 Gas Cap Teardown

One of the most over looked elements of a Honda CT90 or CT200 fuel system is the gas cap used on the gas tank. The gas cap plays a critical role and is designed to allow air to enter the tank and prevent a vacuum from forming as fuel is used by the engine as the CT90 uses a gravity feed fuel system. While allowing the tank to vent air the gas cap also utilizes a labyrinth design to minimize the gas fumes that can escape from the tank.

If the holes in the gas cap become plugged with dirt or rust they will restrict and or prevent air from entering the tank while gas is being consumed by the engine and at some point the vacuum building up in the tank will stop the flow of gas to the engine and the engine will die.

This can be a difficult problem to figure out because once the CT90 dies and you start trying to figure out what's wrong, air leaks back into the tank through the partially plug vents in the gas cap eliminating the vacuum, then gas is able to flow back down to the carburetor and the bike can now start and runs again until a vacuum builds up again and starts the whole process over again.

To avoid these types of issues it is important to keep the two external and one internal vent hole in the gas cap clear and open.

There are a couple of different CT90 gas cap designs and they all contain a chamber or cavity between the outer two vent holes and the inner single hole. I was curious if there was any other baffling within the gas cap so I decided to take a couple and disassemble them to see what if anything was inside.

Warning: I am sharing what I have done working on gas caps on my own bikes as information only and if you chose to work on your own gas cap you do so at your own risk

Later Model CT90 Gas Cap Teardown

I first disassembled a gas cap off of an early 70's CT90 and here are some pictures of the bottom and top of the cap before I disassembled it.

The process to disassemble the cap is pretty straight forward as the top of the cap is really a separate cap that is pressed into the lower cap assembly and just requires driving a small blade screw driver into the interface between the two parts and then prying the upper cap out as shown in the pictures below.

Once I had the two parts separated I found that there was no internal baffling as shown in the picture below.

With the cap disassembled it is now easy to clean up both parts to get rid of all the rust and crud that can clog the vent holes. To reassemble the gas cap you just need to straighten out the rim of the cap you pried out of the main cap and then tap it back in place.

Early Model CT90 and CT200 Gas Cap Teardown

The older versions of the CT90 gas cap are a little more involved to disassemble. Here are a couple of pictures of the bottom and top of an early version of a CT90 gas cap.

This designed is composed of an inner cap assembly that has a single vent hole that is captured in an outer cupped part of the cap that contains two vent holes and then the rim of that component is rolled over to capture the inner cap assembly. You can see the rolled edge in the picture below.

Getting this gas cap assembly apart while straight forward is a little bit of a pain. The basic process was to drive a small screw driver in between the inner and outer cap around the rim and I gently worked my way around the rim prying them apart like shown in the picture below.

Eventually the two parts separated and this is what they look like in the pictures below.

With everything apart the parts are easy to clean and get the vent holes nice and clear.

The challenge came with reassembling the two parts back into a single cap assembly. Since the inner cap is what mates to the gas tank, it really needs to be retained by the outer cap otherwise there is risk putting the cap on a gas tank and then find it can't be removed because the outer cap isn't tightly clamped on the inner cap and just spins.

When I reassembled the gas cap I flared out the rim of the inner cap so it had to be driven lightly to get it back into the outer cap and then I rolled the edge of the outer cap over to secure everything together. Going forward I will most likely won't bother with trying to clean this older CT90 gas cap design as it's not worth the effort and I'll just use the newer configuration that is easier to pull apart and reassemble.

I also made a video on YouTube at the link below that shows the disassembled caps in more detail.

I hope the information I shared above is helpful.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Adjusting the Clutch on a Honda CT90

2020-04-08T09:17:00.001-07:00

I recently did the video at the link below on how to adjust the clutch on a Honda CT90. The method I show in the video would apply to Honda CT200's and many other Hondas that have an automatic clutch.

I hope you find the video helpful.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Registering a Small Motorcycle in the State of Vermont

2020-03-16T21:48:00.002-07:00

Registering a Honda CT90 in Vermont

This post shares in detail my experience in going through the process to register a Honda CT90 in the state of Vermont and then take that registration and use it to get a title here in the state of Washington. I'll explain the process and then share actual copies of the my completed application and what I received back from the Vermont DMV.

I have purchased a number of CT90's that didn't have a title and with the ones that I planned on keeping, I have gone through the "Ownership in Doubt" process here in Washington State that enables you to register and license the bike so you can take it on the road, but there is a long delay in being able to obtain a title. While the process works, it isn't cheap, and you have to go through a three year waiting period before being able to apply for an official title. The three years is supposedly to allow time for a previous owner to come out of the woodwork and claim the bike.

I'm not a fan of Washington State process and had seen several postings on the internet about obtaining a Vermont registration for a small motorcycle and then using that registration to register and obtain a title in a state outside of Vermont, so I thought I would give it a try.

Fact #1 - Vermont does not title motorcycles with engines less than 300 cc's

Since Vermont doesn't title motorcycles with engines less than 300 cc's, I wondered what would happen if I brought in a Vermont registration for Honda CT90 to a Washington State Licensing Office and tried to register the bike in Washington, so during a visit to a local licensing office to renew the registration on one of my cars I asked that hypothetical question to the person who was helping me.

The answer I received was that Washington State respects other states licensing regulations and as long as the vehicle in question had all of the appropriate paperwork required for that state, it would be registered and "titled" in Washington following all of the appropriate Washington regulations.

With that confirmation I decided to proceed with getting one of my CT90's that didn't have a title registered in Vermont.

How to Register a Honda CT90 in Vermont

The process to register a small motorcycle is pretty straight forward and for reference here is a link to the page at the Vermont Department of Motor Vehicles on the process for how you register a vehicle in Vermont that has not been registered before in Vermont.

Fact #2 - Vermont will register vehicles that are not in Vermont or may never be in Vermont.

Fact #3 - The person registering the vehicle in Vermont does not have to be a resident of Vermont or have an address in Vermont.

To apply for a registration of a small motorcycle like a Honda CT90 in Vermont you need the following:

1. You need a Bill of Sale and the Bill of Sale must contain sufficient information to identify the vehicle including Make, Year, VIN, Purchase Price, Mileage, Signature of Seller and Date of Sale

2. You need to complete the Vermont Registration Tax/Title/Application form, VD-119, that is available here at this link. Instruction for how to complete the form can be found here at this link.

3. Back-up documentation on how you established the value for your bike that was used to calculate the tax used on the application form. The NADA Guides are a good resource and here is a link to a page at the NADA website with the values for a 1974 Honda CT90.

4. A check made out to "Vermont DMV" for the total amount shown on the application form. Do not send cash.

5. A Cover Letter - While not required, a simple cover letter is a nice courtesy that helps tie your application package together

Fact #4 - Vermont will only register motorcycles/vehicles that are road worthy and meet all requirements for being able to be driven on the road in Vermont. Vermont will not register a frame or parts bike.

Fact #5 - The Bill of Sale does not have to be notarized.

Once you have completed everything that is required for the application, you take the five items I outlined above and put them into an envelope addressed to the Vermont DMV at the following address:

Vermont Department of Motor Vehicles

120 State Street
Montpelier, VT 05603-0001

If you did everything correctly you should be well on your way to getting a registration back for your motorcycle.

A Real World Example

It's one thing to describe a process and then just leave it at that, but I thought I would go into detail and share with you my actual application package and some of the issues I ran into with getting one of my CT90's registered in Vermont.

Here is a picture of the completed Vermont Tax/Title/Application form that I submitted to the Vermont DMV for my CT90. I crossed out any personal information that I didn't want to share as part of this post and this also applies to other forms that I will share below.

Most of the information you need to include on the above form is pretty straight forward with the upper section containing your personal information. The middle section, and specifically in section 3B, you need to include the name and address of the person you you bought the bike from (should be the same as on your Bill of Sale), and also the date you purchased the bike.

Sections 4 and 5 are very straight forward and are basic information about the application you are making and specific information about you bike.

You need to state the purchase price of your bike in section 6.

In section 9 you need to include the registration fee of $48 which comes from the section on fees at this link and is for a one year registration for a gas or diesel motorcycle.

The tax in section 9 is calculated as 6% of the purchase price or NADA value, whichever is higher. For the $54.60 tax I used 6% of the "Good" value I found at the NADA website for my 1972 Honda CT90 that I was trying to register. The picture below is of the page I downloaded and printed out to include with my application package. I marked up the page to show the value I was basing the tax on.

I also include a copy of the Bill of Sale shown below. I purchased seven parts bikes (these bikes were a great deal!) with this bill of sale so I marked it up to show the specific bike I was trying to register.

I included a person check for the total on the application form and then assembled all of the information above and attached the following cover letter and then sent the package to the Vermont DMV at the address I shared earlier.

While I didn't realize it at the time I sent my package in to the Vermont DMV, I ended up shooting myself in the foot with how I worded my cover letter.

I submitted my application package in early January 2020 and about three weeks later I received the letter below from the Vermont DMV indicating that they were unable to process my application package.

My cover letter had left the impression that the bike I was trying to register "may" not have been a road worthy bike due to me sharing that when I purchased the bike it was a "parts bike". The Vermont DMV was nice and didn't outright reject my application, but just asked me to verify that the bike meets all Vermont highway standards, which I was happy to do.

The Vermont DMV had sent back my entire application package which was interesting as they had marked up the basic application sheet and the NADA page that I had used as a reference for the value of the bike.

With the NADA page they actually had marked it up to reflect that my bike wasn't in as good of condition as I had indicated, which hurt a little, but given it would reduce the tax I would have to pay I wasn't about to argue.

Here is a copy of the marked up application sheet that was returned to me.

The marked up form is interesting as it shows the new tax with the overall lower total, but the other mark-ups or checks give you an idea of the items that are checked with each application package.

The Vermont DMV had also returned the personal check I had sent with the original application, so I voided out that check and then wrote another check for the new lower total and then also wrote a new cover letter to explain that the bike I had rebuilt and was applying to register was road worthy and also included a picture as proof.

Here is a copy of the second cover letter I sent out with the new check and I also included the marked-up application form and NADA page, along with the bill of sale that had been returned to me.

Another couple of weeks went by and then I received the envelope in the picture below in the mail and my started to get a good feeling that I had succeeded.

And I had, as the envelop contained my Vermont license plate along with the final dated application form which is a temporary registration.

Then about a week and a half later I received the letter below in the mail from the Vermont DMV

This ended up being my final official registration and tabs for my license plate.

With the registration card removed from the letter and placing the tabs sticker on my license plate, Was complete and now my CT90 was officially registered in the state of Vermont.

The next step will be to go through the process to transfer my Vermont registration over to Washington state and get my CT90 registered with a Washington State title. I plan on doing that in the next month or so and will come back and update my post at that time.

Status as of July 6th, 2020

With things now getting a little more back to normal I was able to get to my local Washington State Licensing office to request a Washington title using the registration I received from Vermont.

The initial person that helped me at the licensing office was a new trainee, so my request was a challenge for her as she had never gone through the process, but once a more experienced person stepped in to help things progressed well and I received my registration and temporary license for my bike and the title is being sent to me along with my final Washington State plates.

The only quirk I had in the process was that I needed to go back home and get a copy of the Bill of Sale from when I had purchased the bike as part of a group of parts bikes here in Washington. The reason I needed the Bill of Sale was that the second person that helped me indicated that they were going to have to charge me sales tax on the value of the CT90 and without the Bill of Sale they would be using a value of around $900.00 which would have resulted in an addition $90.00+ dollars to the bill. The bike I was seeking a title for was part of a group of CT90 parts bikes I bought where the price averaged out to $57.00 a bike and I was specific when I helped right the Bill of Sale to make sure it reflected $57.00 a bike. So with the Bill of Sale I only ended up paying several dollars for theses tax and the total bill ended up being $174.00. That final bill included a $35.00 fee for what is known as "collector plates" here in Washington that results in me never having to pay any additional registration fees, ever!

So my total bill going through both the Vermont and Washington processes was about $260.00 which I think is pretty good and not much more then what I would have had to pay to go through the Washington "Ownership in Doubt" process and eliminates the three year wait to get a real title.

I think the primary lesson learned from that last part of this overall effort is to find a Washington State licensing office that has someone who is experienced and knows the process. My first couple inquires at a couple local offices were met with some blank stares, but once you find the person who has the experience and understands nuances of other states, they just process your transfer request like any other request they receive.

I hope this post was helpful in showing you what is involved with registering a small motorcycle in the state of Vermont.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

For Sale - The Original Made in the USA Honda CT90, CT110 & CT200 Clutch and Headset Nut Tool

2019-10-26T11:39:00.012-07:00

As of May 26th of 2021 I am now out of stock of my tool. I am looking into making another batch, but the outfit I use to laser cut my tool has increased their prices significantly to where it may not be worth the effort to continue to try and sell my tools, especially given how cheap the knock off of my tools are coming out of China. I'll update this post if I do end up producing another batch.

I do want to thank everyone who has purchased one of my tools as it has been an enjoyable experience (except for the knock off's from China...) and I hope you have found the tools useful.

As of April 2021 - I have parts in stock here at my link on eBay and now at a lower price of $26.00 plus $5.35 for shipping. I also am including for a limited time, a prototype of my 3D printed valve spring compression tool that you can learn more about at my blog post here at this link.

I have lowered my price and included my valve spring compression tool to compete with sellers from China who have made a knock-off of my tool (which they also make in China) and are now selling them on eBay which kind of sucks. The turkeys are also using the pictures from my eBay listing which I can't do anything about according to eBay which doubly sucks as my own hand is in the pictures.

To compete, I've gone out on a limb and made a larger batch of tools which has enabled me to lower my price and still be able to make here in the USA!

When working on a Honda CT90 two of the most frustrating things can be trying to hold the clutch basket while loosening the nut that holds it on and also loosening the special headset nuts on the front forks. Like most people I have found ways to get the job done and even made a post about using plumbers tape to hold the clutch basket, but I really wanted a nice tool since I plan on working on CT90's as a hobby for a long time, so I decided to design and produce my own.

After a couple iterations, I ended up with the tool design shown in the picture below that works on a CT90 and CT200's in addition to some other Honda models, and I am currently selling them on eBay for $26.00 plus $5.35 for shipping. Here is the link to the listing on eBay.

Here is a picture of the tool being used on a CT200 engine.

Instead of just having the tool be good for holding the clutch basket, I added some openings on the handle and one edge of the tool that can be used to loosen the headset nuts on the front forks of a Honda CT90.

The largest opening on the handle fits the lower headset nut found on most K2 and newer CT90s and fits as shown below.

The smaller opening at the end of the handle fits the smaller upper headset nut on most K2 and newer CT90's in addition to the headset nut found on K0 and most earlier CT90's and fits as shown below.

And last, but not least, I added a feature along the edge of the tool that fits the headset nut on the K1 version of the CT90 and is shown in the pictures below.

Again, if you are interested in picking up one of these tools I am selling them on eBay at this link. I currently am selling these within the USA, but due ship outside the USA using the eBay global shipping program.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Product Review - Memotronics ELF33-6 Turn Signal Flasher

2019-10-07T22:08:00.002-07:00

I have a 1975 CT90 that I have never had the turn signals work all that well even though I replaced all the bulbs, picked up a new stock flasher, and cleaned the truncates signal switch and also went through and checked and cleaned all the grounds.

While I did get some improvement after taking all of the steps described previously, they still didn't work like they should, so I decided that I would take the next step and look at converting my turn signals to LED bulbs.

In making the change to LED's I knew it couldn't't be a straight swap of the bulbs only and that I would need to change the flasher to a configuration that wouldn't be dependent on the resistive load of the bulbs to cause the flasher to function like with a stock CT90 flasher. So I figured I would do the upgrade in stages and first buy a new flasher that works with LED's and with a little searching on Amazon I found the Memotronics ELF33-6 Turn Signal Flasher that had good reviews.

Here is a link to the flasher on Amazon:

The flasher is different from a stock flasher in that it contains a ground wire that must be grounded to the frame of your CT90 and also contains an extra output blade that gives you the option to drive the turn signal indicator light in your speedometer directly if you so choose.

Since my goal at this point was to just change my stock flasher with this one to see if it made any improvement I decided to make a couple of simple modifications to the flasher.

The changes I decided to make were to add a change the connector on the end of the ground wire to a closed eye and also to add a short section of shrink tubing to the extra output blade that provides the optional method to power you indicator light.

Here is how the flasher looks after I made the changes.

The photo below is of the bottom of the flasher and shows the labeling of the blades that are used to connect to the wiring on your CT90.

The blade on the right with an "X" above it is what connects to the wire providing power to the flasher on you CT90 and that wire is generally black in color.

The lower blade that I have applied heat shrink tubing too and that has a "P" label to the right is the optional output from the flasher that can be used to drive the turn signal indicator lamp in your speedometer. I may use this output when I finally change my bulbs to LED and I'll do an additional post at that time to explain how I run and hook up that wire.

The blade on the left with an "L" below it is the output that will actually drive your turn signal lights and that connects to the grey wire on you bike that was connected to your stock flasher.

Here is a picture with the flasher connected to the flasher wire on my CT90, but not not installed in its rubber holder and the ground wire not yet installed.

And here is a picture of the final installation with the flasher in its holder and the ground wire installed.

With the Memotronics ELF33-6 Flasher installed my turn signals now come one much quicker, flash a nice rate and are brighter then they were before, so it was a noticeable improvement. The flasher isn't cheap at $17.99, but is needed for LED's which I plan on using in the future and a definite improvement over the stock flasher. So if you are having issues with your turn signal lights on your CT90 you might consider using this flasher.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

CT90 Engine Exposed!

2019-08-26T09:26:00.001-07:00

I was finally able to get around to doing a project that I have been wanting to do for some time and that was to take a bunch of extra CT90 engine components and build an engine using cases that I had machined to end up with an engine that would enable you to see all of the internal components.

Related Posts:
CT90 Engine Reassembly
CT200 Engine Reassembly

Here is a picture of how the final engine turned out.

Once I had the engine built up I decided to make a video and share it on YouTube. In the video I show the engine running and also provide detail views showing the changing gears, operating the clutch, and how the piston and valves interact. I also included some slow motion video that really provides insight on how the internals of a CT90 engine work.

Below is a link to the video on YouTube:

I hope you find the video interesting and informative as I enjoyed really enjoyed pulling together this project.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Honda CT200 Step by Step Engine Reassembly Guide

2019-05-24T12:58:00.001-07:00

I recently picked up a CT200 that wasn't running, but seemed to be in decent shape where the engine would turn over and had signs of good compression. I had rebuilt one CT200 a couple of years ago and sold the bike and since that time I started this blog and because I have had such a good response with the post I did on reassembling a CT90 engine, I decided to take the time to go through the engine of my new CT200 and document the reassembly in this post. Another reason I am going through this engine is that this may end up being a bike I will keep for a while and it seems like all old CT's that I pick up have slime in the engine and the clutch will end up slipping sooner or later, so now is as good a time as any to tear it apart, clean, and then reassemble the engine to avoid any problems in the future. I plan on taking the same approach I did with the CT90 engine reassembly post where I document in detail the step by step process on how everything goes back together in case others were interested in knowing what the inner workings of a CT200 push rod engine look like.

Links to Related Posts:
My Honda CT90 and CT200 Clutch and Headset Nut Tool
Cut away of CT90 Engine - CT90 Engine Exposed!
Honda CT200 Engine Fasteners
Repairing Damaged CT90 Spark Plug Threads Using a Time-Sert Thread Insert
CT90 Clutch Pack Assembly Detail Build-up
Painting Honda CT90 Side Cases
Making a Low Cost Clutch Holding Tool for Your CT90
Building a Basic Timing Light fro a Harbor Freight LED Light
A Simple Valve Spring Compressor
A Simple Way to Check Your Valve Seats
Product Review - Shindy Valve Set 07-002

If you've thought about tearing your own CT200's engine apart, but have avoided it because you thought it might be two difficult, you should really give it a try. The CT200 engine is really a very easy engine to work on and is difficult to screw up when you reassemble it as everything goes together so easily.

Also, if your interested in how the inner components of a CT200 engine actually work, please take a look at a video I made here at this link which shows in detail the inner workings of an operating CT90 engine using a cut-away engine I machined up. While the CT90 uses an overhead cam compared to the push-rod CT200, the clutch and transmission are very similar between the two engines. When I get enough spare CT200 engine parts I plan on making a similar video.

As I outline how I go about reassembling the engine, I may not use the official terminology for what each one of the parts may be called by Honda, but you should be able to get an idea of which physical part I am talking about. There are a number of fasteners that should be properly torqued during the assembly process and while I don't call out those torque values here you can easily look them up at the links I have to Honda manuals on my Helpful Links page.

Here is a shot of the engine at the end of the rebuilding effort.

Before I started reassembling the engine, I took everything apart and cleaned and inspected all the parts, replaced any screws or fasteners that got buggered up during the disassembly process. I didn't do it with this engine, but I think its always a go idea to switch out all of the fasteners that hold the cases together to socket head screws which I think is well worth the cost as it makes it very easy to disassemble the engine in the future.

Here is a picture of the majority of the parts that go into a CT200 engine. The side cases shown were painted following a process I shared in another post I made here at this link on how to paint your ct90 side cases.

One item that helps make the assembly process that much easier is a simple engine stand made from four pieces of wood like the one I use in the picture below.

The dimensions for the stand that I use are that it is 13 inches long, 10 1/8 inches wide, and 5 1/2 inches high. I made mine from a scrap 2 x 6 I had in my shop. Having some sort of stand like this does make the assembly process that much easier.

Before you get started you will also need to have a set of gaskets and shaft seals. For this CT200 engine I purchased a Bee gasket set on eBay which seems to have the best price, but it is also available here at this link on Amazon. For the shaft seals I ordered off of eBay that seem to work just fine.

The one thing I did find with the Bee gasket set that it wasn't really complete as it was missing the oil pump gaskets, the gasket that seals the oil screen cover, and the thin o-ring that goes on the cover for the clutch assembly. I was able to order the gaskets for the oil pump and oil screen off of eBay, but I couldn't find the o-ring for the clutch cover, but I was lucky that the one I have is in good enough shape to reuse.

Another detail worth pointing out is that it is always a good idea to apply a little oil or assembly lube to any metal surface that will run against another to help provide some lubrication during the initial start-up of the engine prior to the oil getting circulated. I use Permatex Ultra Slick also available on Amazon.

The first thing I did in starting to put this CT200 engine back together was to do some sub assembly work on the center and side cases. I'll start with installing the parts that make up the oil pump assembly into the left side case that will ultimately hold the generator assembly.

Here are the parts that make up the oil pump assembly:

I'll start by assembling the oil pump first and then install it into the housing. The first step is to install the loose gear of the pump with a little lube on the post on the aluminum half of the pump housing.

Next I'll install the gasket that goes between the two major components that make up the oil pump.

I noticed that the gasket partially covered one of the holes in the housing so I took an excato knife and tried the gasket as needed to unblock the hole.

I then installed the steel housing half of the oil pump that has the other gear already installed on to the aluminum half of the pump. I then turned over the assembly and installed the two shorter screws that hold these two housings together and then the pump was ready to install.

I next placed the base gasket for the oil pump in the left center housing and installed the pump using the four longer screws.

To make sure that there is nothing wrong with the installed oil pump assembly, I'll take the cam shaft and insert it from the inside of the housing so it is engaged with the feature that drives the oil pump and rotate the oil pump to verify that the internal gears of the pump rotate freely.

Next I will install the three seals that go into the left center housing starting with the seals for the output shaft that will hold the drive sprocket and the gear shift shaft.

When installing seals like these I will generally apply a very light coat of RuGlyde to the outside diameter of the seal our interior pocket of the bore to help with the installation. RuGlyde is a rubber lubricant for mounting tires, but has a number of other uses and is handy to have around the shop.

I will use something like the back of a socket that is close to the diameter of the seal as a seal driver and lightly drive each seal into place.

Following the same process I will install the seal into the opening for the crank that keeps oil from the generator cavity. In this situation I used a scrap block of wood as a seal driver and installed the seal so that it was flush to the rim of the hole it was being installed into.

Next I will move to the right center housing and install the oil screen components, cover and drain plug on to the bottom of the housing.

I'll place the housing with the oil filter cavity facing up to make the installation easier.

I'll next drop in the oil screen followed by the oil screen support and then place the gasket for the cover and install the four fasteners that hold on the cover.

Lastly I'll install the drain plug and the aluminum crush washer that its as a seal for the drain plug.

Next I move on to the clutch case side cover to install the seal for the kick start shaft and also the small drain plug near the front of the cover.

First I'll install the small bolt and aluminum crush washer that is the seal for the bolt.

These go in the threaded hole on the bottom of the cover towards the front.

Next we'll install the seal for the kick-start shaft following the same approach as was used with the other seals installed earlier.

The next step is to build up the sub assemblies that make up the transmission and I'll start with the shifting fork assembly which includes the parts in the picture below. Some people may not disassemble this assembly, but I always do just to make sure and get all of the crud out of the nooks and crannies.

The first step is to install the shifting fork on each end of the assembly with the small width fork installed from the end with the short stub shaft and the wider shift fork installed from the end with the plate that has five holes.

To install the shift fork slide it over the appropriate end until the threaded hole is over the slot on the shift drum that runs around most of the diameter of the shift drum.

Next place the washer with the locking tabs over the threaded hole making sure the larger tab is engaged with the straight edge of the raised boss of the threaded hole and then install the special bolt and tighten.

With the bolt tightened, fold up the tabs on the washer against the flats of the bolt head to lock it in place.

Now repeat the same steps to install the other shift fork on the other end of the shift drum as shown below.

The next step is to install the headed pins and the retainer plate on the end of the shift drum.

If you are missing any of the pins here are their dimension in inches.

The head on all of the pins is .194 inches in diameter and .106 inches long.
The length of the straight section of the four longer pins is .475 inches long
The length of the straight section of the one short pin is .100 inches long
The diameter of the straight section of both the short and long pins is .055 inches in diameter

With the five holes on the plate at the end of the shift drum four are deep and one is shallow. When the pins are installed the head of the pin should be setting on the plate, so if you insert the long pin in the shallow hole it will protrude out which is incorrect as shown in the picture below.

Install the short pin in the shallow hole and then proceed to install the remaining four long pins as shown below.

The next step is to install the plate and screw that retain the pins.

I apply some blue Loctite to the screw to help make sure the plate won't come loose.

The last step for this assembly is to install the copper component that provides a ground to the neutral light.

To install this component it is slipped over the small shaft on the end of the shift drum while aligning the hooked end with the small hole on the same end of the shift drum.

And then gently work the hook down into the hole until the copper component is seated at the base of the shaft as shown below and then this assembly is complete. While I didn't do it hear, this would have been a good time to clean any oxide off the copper component to help ensure you always will have a good ground for your neutral light.

The next step is to assemble the two gear and shaft assemblies that make up the transmission.

Here are the components that make up the first assembly that contains the shaft with the interface that will ultimately accept the chain drive sprocket.

These components assemble in a straight forward manner with the intermediate slid down the shaft with the square dogs mating with the square dogs on the gear that is already on the shaft assembly.

Next the remaining gear is slipped down on the shaft facing the pins on the gear that was just installed. This gear is symmetric and can be installed either way.

Lastly the thrust washer is slipped over the end of the shaft.

Here are the components that make up the second shaft assembly.

This is assembled in the same manner as the previous assembly with the square dog end of the intermediate gear facing the square dogs on the gear that is part of the shaft assembly.

The last gear to be installed is not symmetric and must be installed with the side that has bottomed holes facing the pins on the gear that was just installed.

The last step is to install the thrust washer on the end of the shaft. You can add a little assembly lube to one side of the thrust washer to help it stick to the last gear that was installed as the washer will be facing down and potentially come off when this assembly is finally installed in the engine housing.

The next step is to assemble the two shaft assemblies to the shift fork assembly as shown in the picture below.

The two shaft assemblies are rotated towards each other while remaining engaged to the shift forks as shown below (the one lower gear at the end of the shaft slipped downbeat was moved back to its correct position when it was installed into the engine housing).

The collection of assemblies are then installed into the left center engine housing as shown below.

The next step is to install the components that make up the kick starter assembly.

The first step in building up this assembly is to install the pawl into the pocket as shown below and then spring that actuates the pawl.

The next step is to install the large spring on the assembly

The next step is to install this assembly into the left center engine case so the the tang on the large spring engages the slot in the housing as shown below.

The next stem is to install the plate with the positioning pin down over the kick starter shaft and then you will have to rotate the shaft assembly that was just installed counterclockwise slightly so that the pin in the plate can engage the hole in the housing and be set down in its final position as shown below.

Next one of the two thrust washers is installed down over the lick starter shaft

This is followed by the installation of the gear and then the last thrust washer

The next step is to install the crank assembly.

The crank drops into the center left engine housing as shown. You might apply a little oil to the lip of the seal that the crank will be passing through to help it more easily slip over the shaft feature the seal will be running on.

The next step is to install the gasket that goes between the two housings and then install the right side center housing.

Sometimes a few very light taps of a plastic hammer can help the housing settle down over the guide bushings and the crank. When using a plastic hammer its the light vibration of the taps that help everything seat and you don not want to apply any hard blows that could potentially damage any components.

To install the screws that hold the two cases together you will have to flip what you have already assembled while holding the cases together.

Next install the screws that hold the two cases together and torque to the specified value.

This is a good time to also trim the excess gasket at the interface where the cylinder will seat.

The next step is to install the bolt that retains the shift fork assembly. Depending on how you like to do things this good have been done earlier if desired.

To get the bolt started you may have to push up on the other end of the shift fork assembly.

And then to tighten down on the bolt the engine may have to come off the wood stand so that a large screw driver can be installed into the screw on the shift fork assembly that holds the pin retainer plate as shown below.

The last step is to install the rubber plug that covers the bolt that was just installed and it is simply placed over the hole and tapped into place.

The next step is to assemble and install the components that make up the gear shift shaft and the shift drum stopper.

The first step is to install the small spring on the arm that interfaces with the shift drum.

Next the arm assembly is slid down on the gear shift shaft and secured with a retaining ring as shown in the following pictures.

The next step is to install the large spring as shown in the photo below.

Before the gear shift shaft assembly can be installed in the engine the thrust washer needs to be placed over the hole the shaft will be installed into.

Next the gear shift shaft assembly is installed into the hole and slide down until it rests on the housing and then the arm is engaged in the slot with the pins on the shift drum as shown in the pictures below.

To install the shift drum stopper the spring is attached to the stopper and then stopper is placed in position and the special bolt is installed using blue Loctite as shown in the pictures below. The shift drum stopper ends up ridding on the head of the pins in the shift drum.

The next step is to install the push rod lifters followed by the cam shaft and timing gear assembly.

The push rod lifters could have been installed earlier when the two center housings were apart, but I chose to wait until now so I wouldn't have to worry about the lifters dropping out of the bores they are installed into while I was handling the engine. It is a little awkward at this step in the process but very doable.

To install the lifters, I will fist add a little assembly lube and the using a magnet I lower each lifter through the opening for the cam shaft and then install one in each of the two bores as shown in the pictures below making sure they are fully seated so they won't interfere with the camshaft when it is installed.

The next step is to install the timing gear to the camshaft. The end of the camshaft that accepts the timing gear has a pin to clock the timing gear to the camshaft. The timing gear is secured to the camshaft with a bolt and washer and its a good idea to add a little blue Loctite to the threads of the bolt.

The next step is to install the camshaft assembly and I'll first apply a little assembly lube to the cam lobes and journals on the camshaft.

When installing the camshaft assembly you have to make sure of two things so the camshaft is installed correctly. The first is to make sure the small pin on the end of the camshaft that drives the oil pump is aligned so that it will pick of the flat drive feature on the oil pump while at the same time you also get the alignment mark on the camshaft timing gear (an "O" stamped between two teeth on the gear) aligned with the timing mark on the crank shaft timing gear.

So taking all of the alignment that needs to be done, install the camshaft assembly.

Here is a close up of the two alignment marks on the timing gear after they are installed and this position is also top dead center (TDC).

As a side note, when I was initially putting this engine back together I noticed that the timing gear on the crank assembly no longer had a timing mark for whatever reason, so initially I thought I was going to have issues getting the timing gears installed correctly. I then remembered that I had taken photos as I had disassembled the engine and went to the photo below where I was able to identify the tooth on the crank timing gear that would align with the timing mark on the camshaft timing gear. With the picture I was able to look at the stains and other markings on the crank timing gear and go back and identify the appropriate tooth and then I used a center punch to make a new small timing mark.

The next step is to install the drive gear shown in the picture below. This step is pretty simple and it just involves placing the drive gear on the shaft and then install the retaining ring that holds it in place.

The next step is to install the small assembly that directs oil to the timing and drive gear interfaces.

On the one end of the assembly with the banjo fitting there are two aluminum washers that need to be installed. The first goes between the banjo fitting and the housing.

Then position the assembly as shown below.

Next place the second aluminum washer on the banjo fitting and install the hollow bolt taking care not to over torque and shear the bolt.

And the last step is to install the screw at the other end of the assembly and then this step is complete.

The next step is to install the clutch pack assembly. I am not going tp detail how to assemble a CT200 clutch pack assembly here, but I did do a detailed post on how to build up a CT90 clutch pack assembly which is almost identical. Here is the link to the CT90 clutch pack assembly post. I will include the photo below of how the clutch disks and plates are arranged in a CT200 clutch pack to go along with the information provided in the CT90 clutch pack link to help you make sure that you get your CT200 clutch pack assembled correctly.

Here are the clutch pack and associated components from our CT200 that we will install next.

The first step is to install the bushing over the shaft of the crank.

The next step is to install the clutch pack assembly onto the crank shaft and get it engaged with the drive gear.

The next step is to drop in the lock washer and make sure the inner tabs are engaged with the slots/splines of the clutch pack assembly.

Next install the nut that will retain the clutch pack and use a tool to hold the clutch pack (not shown) and a special tool to torque down the nut with a torque wrench.

I also now sell the clutch holding tool in the picture below that I designed and that can also be used to loosen the headset nuts on most Honda CT90's and CT200's. Here is a link to the post I did that includes a link to where I sell the tool on eBay.

With the nut torqued down fold up one of the tabs on the lock washer into the nearest slots on the nut like what is shown in about the 2:30 position in the picture below..

Next install the stamped sheet metal divider into the center of the clutch pack opening.

The next step is to install the cover on the clutch pack assembly. The cover has an o-ring that has an ID of 1.90 inches and a .060 diameter cross section which is first installed in a groove on the cover.

Next install the cover using the two countersunk head screws.

With the clutch pack installed which now gives us a way of holding the crank we'll flip the engine over and install the remaining components on the left side of the engine.

The first thing we will install is the alternator stator assembly.

The alternator stator is installed by lining up the wire bundle rubber grommet with the opening in the housing and then setting the stator in place lining up the three appropriate holes in the stator with the three threaded holes in the housing and then install and torque down the mounting screws.

The next step is to install the components that make up the other half of the neutral switch that are shown in the picture below. The neutral switch is really just the copper tab on the shift drum and this neutral conductor encased in a black plastic. When the copper tab on the shift drum comes in contact with the nub at the end of this component it completes the ground path for the neutral light.

The first step is to install the conductor in its hole in the housing making sure the o-ring is installed on the end of the conductor. The straight edge on the rim of the conductor should face the thread hole for the screw that will lock down the conductor retainer.

Then install the retainer and screw.

To attach the wire from the neutral light the conductor has a spring loaded washer at the top end which is depressed and then the end of the wire is inserted in the through hole at the top end of the conductor. When you release the washer it will hold the wire in place.

The next step is to install the alternator rotor and the spark advancer. I have a post at the link here on how to assemble a CT200 spark advancer.

The first step is to install the alternator rotor by lining up the keyway slot in the rotor with the key on the crank shaft and then install the rotor.

Next line up the pin in the base of the spark advancer with the keyway on the top of the alternator rotor and set in place.

Next install the washer and bolt that retains the spark advancer and alternator rotor and torque to the appropriate value. To torque the bolt you will most likely need to remove the engine from the wood block and use a suitable retaining tool on the clutch pack assembly. Also, if you are so inclined you may want to add a little blue Loctite to the threads of this bolt before installation.

The next step is to install the cover for this portion of the engine.

First install the gasket which is then followed by the cover and screws.

The next step is to install the points and condenser plate assembly.

To install this assembly simply set it in place as shown in the pictures below making sure the wire that will go to the points is not trapped underneath.

Next install the two screws that retain the assembly, but leave them loose enough so the plate can still be rotated by hand.

To attach the wire for the points, first depress the spring loaded wire retainer as shown in the picture below so that there is an opening for the wire. Insert the bare end of the wire and release.

The installation is now complete and we will come back later after the engine is fully assembled to adjust the points and set the timing.

The next step is to install the drive sprocket.

First slip the drive sprocket on the output shaft.

Next slide the retainer plate down over the splines of the output shaft until it is in line with the groove in the output shaft and then rotate the retainer plate in the groove until the holes in the plate align with the threaded holes in the drive sprocket as shown below.

Lastly install the two short bolts that secure the drive sprocket to the retainer plate.

With that complete we will flip the engine over in the wood block so that we can complete the assembly of the right side of the engine.

The next step is to assemble the components that actuate the clutch pack when you move the gear shift pedal.

The first component to install is the bearing that goes in the bore on the end of the clutch pack.

That is followed by the ball-ramp assembly that slips into the inside diameter of the bearing we just installed.

Next we will install the arm that slips on the gear shift shaft and mates into the notch on the ball-ramp assembly we just installed. The important detail with this step is to make sure the arm is pointing at the center of the clutch pack when it is installed.

The next step is to slip the thrust washer over the end of the gear shift shaft so it rests on the arm we just installed.

The next step is to install the small spring loaded plunger into the center of the ball-ramp assembly. First assemble the plunger on the spring and then drop it into the center of the ball-ramp assembly.

The last step with installing these components is to place the large diameter spring over the raised rim at the center of the ball-ramp assembly.

We will next install the right side cover, by first installing the appropriate gasket, then the cover and finally the screws that retain the side cover.

The final step to finish off the right side of the engine is to assemble the adjustment mechanism for the clutch to the cover and then install the cover.

First take the threaded shaft and thread it into the stamped ball plate as shown below and then insert into the cover making sure the get the anti-rotation pin in the bottomed hole on the back side of the cover. Its also important to make sure the o-ring is installed on the threaded shaft and this is another seal that didn't come in the gasket kit I purchased so don't lose the one that was on the shaft when you disassemble your engine.

The last step to finish the installation of the adjustment mechanism to the cover is to install the washer and lock nut on the exposed end the the threaded shaft on the outside of the cover.

The next step is to install the clutch cover on the on the case by first installing the appropriate gasket, then the cover, and lastly the screws to retain the cover.

With the cover installed this is a good time to go ahead and do an initial adjustment of the clutch following the instructions in the Honda CT200 maintenance manual.

For the next step we will reposition the engine on the wood block and begin assembling the top end of the engine.

The next step will be to install the rings on the piston and then assemble the piston onto the piston rod.

We'll start with installing the rings on the piston. I'm not going to go into any detail about checking the end gap of the rings, etc. as I have never really bothered to check that on any bike or car piston I have installed over the last 45+ years and have never had a problem. Maybe I'm just lucky, but I think it is more that any automotive or motorcycle manufacture could never afford the time required to do that sort of check in a production environment and the focus is more on holding manufacturing tolerances tight so it won't be an issue.

I am also not going to try and explain in detail how to install each ring as there is a feel to it, so I'll just say that if you haven't done it before take your time and try not to break the compression and scraper rings as they are brittle. If you do end up breaking a ring well welcome to the club and now you with hopefully have the experience that you won't do it again with the next set of rings you have to buy.

On the page I have on video links I do include this link here which is a very nicely done video on how to install piston rings and is a good guide if you have never done it before.

Getting back to assembling this engine, there are there rings that need to be installed.

The top ring is the compression ring.
The next ring down is the oil scraper ring
And the bottom ring is the oil ring and can either be an assembly of three rings or is a single wide ring as is the case for this engine I am building here.

The first ring I will install is the oil ring and you will always want to install the lowest ring first and work up to installing the compression ring last. All rings will be marked something like what is shown in the picture below and the markings always face up towards the top of the piston.

And here is the oil ring installed in the piston.

Next is the oil scraper ring and agin install with the numbers facing up.

And the last ring to be installed in the compression ring agin with the markings facing up.

If you installed all three rings correctly it should look something like the picture below. When you actually go to install the piston in the cylinder you will want to make sure the gaps between all the rings are approximately 120 degrees apart and I prefer to have those gaps on either the left or right side of the piston and not directly on the top or bottom of the piston. Having the gaps staggered helps create a labyrinth seal for any gas that escape through the first gap in the compression ring.

The next step is to install the piston on the piston rod and the important detail here is to make sure the arrow on the top of the piston is pointing down as shown in the picture below.

To install the piston slide it over the end of the piston rod and align the bore for the wrist pin with the bore in the end of the piston rod and then slide the wrist pin through the piston and piston rod until it is centered.

The last step is to install the small clip in each end of the wrist pin bore in the piston to retain the wrist pin.

The next step is to install the cylinder.

First install the gasket over the studs and then start to slide the cylinder down over the studs to the piston.

At this point you want to check and make sure your piston rings are oriented correctly and I will tend to apply assembly lube to the bore, piston and rings.

The end of the cylinder that first engages the piston is chamfered to help with the installation of the rings. I will compress each rings with my finger and work it into the bore one at a time while also hold the piston as I slide the bore down. If you have a large oversize bore there may not be much of a lead in chamfer left, but if you keep at it you'll be able to get the rings compressed and in the cylinder.

Another way to help hold the piston as you try and slide on the cylinder is to put a 14mm wrench on the head or the bolt for the rotor and spark advancer as shown below.

The next step is to build up the cylinder head.

To install the exhaust valve, lubricate the stem and then insert it into the correct hole in the cylinder head. Then on the other end install the inner spring, outer spring and cupped washer that will retain the valve stem retainers.

The next step is to use a valve spring compressor to compress the springs so that the valve stem retainer clips can be installed.

I use a simple tool that I made which utilizes a C Clamp that does the job. I made a post on the method and tool I use here at the following link.

With both retainers installed, remove the spring compressor and the installation of the valve is complete.

Repeat the exact same steps with the intake valve and then the cylinder head assembly will be complete.

The next step will be to install the cylinder head and associated seals on the engine.

for this step it can make things easier if we first re-orient the engine in the wood block so that it is pointing up which will help keep several of the small seals in place during their installation.

Another assembly aid is to apply a very small amount of the assembly lube to each seal as it is a sticky lube and will help hold each seal in place.

Install the three o-rings in there respective positions as shown in the picture below.

Next install the square cross section o-ring in the lower right position as shown below.

The last step before installing the cylinder head is to position the head gasket. I will use small amounts of the assembly lube on the head gasket to help it stick to the cylinder head while it is being lowered into position as shown below.

With the cylinder head now in position holding all of the seals in place the engine can be re-oriented in the wood block for the next step where the rocker arm assembly will be installed.

Here are the components that make up the rocker arm assembly. Its also a good idea at this point to set the adjustment screws on each rocker arm so they are at their loosest setting which will make it easier later on when we go to adjust the valves.

Starting with the longer rocker arm, assemble the spring to the hub of the rocker arm as shown below and then compress the spring and place the rocker arm and spring into the housing with the spring facing the opening that the rocker arm shaft will be inserted through.

Next install the shaft for the rocker arm with a little assembly lube or oil into the bore until it is fully seated.

The next step is to install the short bolt and aluminum washer into the opening that you just installed the rocker arm shaft through and tighten the bolt.

The next step is to follow the same process to install the shorter rocker arm & spring, rocker shaft, and bolt and aluminum washer.

The next step is to install the rocker arm assembly on to the engine.

We first will install the push rods with the long push rod installed into the left hole as you're facing the engine and the shorter push rod being installed in the right hole.

Next install the gasket for the rocker arm assembly as shown below.

Then install the rocker arm assembly over the mounting studs.

Next install the nuts that retains the top end paying attention to make sure that the copper washer and cap nut are installed on the upper left stud as shown in the pictures below. The copper washer acts as an oil seal for the pressurized oil that is being supplied to the cylinder head and rocker arm assembly along this stud.

The final step is to torque these nuts to the value specified in the Honda manual and also following the pattern defined in the manual.

With the basic engine assembled, we will now turn our attention to making some final adjustments to the valves and points and then setting the timing before installing the final covers.

The first thing we will do is adjust the valves and to do this we turn the crank as needed so that the piston is at top dead center on the compression stroke. When you are at top dead center on the compression stroke the timing pointer should be pointing at the mark next to the "T" on the alternator rotor as shown in the picture below and both rocker arms should be slightly loose.

With the engine at top dead center adjust the intake and exhaust valves so there is .002 inches of clearance. Standard practice is to use a feeler gauge to set this gap, but if you are in a pinch and don't have a .002 inch feeler gauge you can screw down each post until it just touches the top if the valve stem and then back it off 1/8 of a turn and that will leave you a gap of about .0024 inches.

Once you have each gap set, tighten the lock nut while holding the adjusting screw/post.

With both valves adjusted, its time to install the two valve access caps.

Install a new o-ring on each cap as shown and the install into threaded openings on the rocker arm assembly.

With the valves adjusted the next step is to adjust the gap on the points assembly.

To Adjust the points to the correct gap we first need to rotate the engine counterclockwise using a 14mm wrench on the head of the bolt holding the spark advancer until the gap on the points are at their widest position.

At this position we use a feeler gauge to check the gap and see if it is in the range of .012 to .016 inches. While any gap in the range is acceptable, I generally shoot for the lower end as it allows more time to saturate the coil at higher RPM's which helps ensure a good strong spark.

This is also a good time to clean the contacts on your points if the are not flat or clean. If you do feel you need to file your points go very easy and remove the least amount of material possible and the clean with contact cleaner so that they are clean and dry when you are down.

The following picture points out the key features related to adjusting your points gap.

So, again use a feel gauge to check the gap as shown below.

If you need to adjust the gap, slightly loosen the two mounting screws as shown below.

Then turn the small adjuster feature until you have the desired gap and then tighten down the two mounting screws. It is always a good idea to recheck the gap after tightening the mounting screws to see if you still have the desired gap.

Your points may look slightly different then the points shown in the pictures above as Honda used more then one supplier for points assemblies, but the process should be similar for other brands of points.

This is also a good time to add a very small amount of lubricant to the felt pad where it contacts the cam on the spark advancer. The lubricant helps minimize the wear of the leg of the points that rides on the cam. I use the lube shown in the picture below and I use it very sparingly as I do not want any of the lubricant to ever make its way to the actual points contacts.

The last major step before we can finish the assembly of the engine is to adjust the timing.

At a minimum you will need a static timing light to set your timing and I have a post where I shown how to make a basic static timing light from a almost free Harbor Freight LED light at the link here.

The following picture points out some of the key features involved with adjusting your timing.

The picture below is how I connect my static timing light. One lead from the light goes to the black wire in the engine harness coming from the points and the other lead from my light goes to a ground on the engine. When the points close the light should come on and when the points open the light should go off.

With the static timing light connected if your timing is set correctly then the light should go off just as the line next to the "F" comes in line with the line on the pointer while rotating counterclockwise on the compression stroke.

If your timing is a little off one way or the other, loosen the two screws that clamp down the points plate so it can rotate as shown below.

Then use a blade screwdriver in the adjusting slot to rotate the points plate either clockwise or counterclockwise to get the timing light to go off just as the line next to the "F" comes in line with the line on the pointer.

Once your timing is finally adjusted correctly it should look like what is shown in the following video.

With the timing complete its time to complete the assembly of the engine by installing the remaining parts shown below.

The access cover has an integral molded rubber gasket and installs with two screws.

Next install the spark plug.

And lastly install the oil fill cap/dipstick.

And with that the engine is now complete.

With this engine I will add oil and kick it over a few times to circulate the oil through the engine as it will not be going back on to the CT200 it came off of for some time. I will also add some sort of plug to the opening for the intake manifold and exhaust port to prevent anything from getting into the engine while it is waiting to be reinstalled.

I hope you found this post useful and if you have been hesitating rebuilding your own CT200 engine, don't as it is actually a very simple and straight forward task that I personally also find very enjoyable.

Links to Related Posts:
Honda CT200 Engine Fasteners
Repairing Damaged CT90 Spark Plug Threads Using a Time-Sert Thread Insert
CT90 Clutch Pack Assembly Detail Build-up
Painting Honda CT90 Side Cases
Making a Low Cost Clutch Holding Tool for Your CT90
Building a Basic Timing Light fro a Harbor Freight LED Light
A Simple Valve Spring Compressor
A Simple Way to Check Your Valve Seats
Product Review - Shindy Valve Set 07-002

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 & CT200 parts available on Amazon

Honda CT200 Engine Fasteners

2019-04-16T20:49:00.004-07:00

I put this post together as reference for the length of the fasteners used in a 1964 Honda CT200 for assembling the engine cases and covers, but also for some of the fasteners used internally within the engine.

Screw size convention
Example: M6 x 1.00 x 20
M6 - is the diameter of the screw, which in this case is 6mm
1.00 - is the thread pitch of the screw in threads per millimeter
20 - is the length of the screw, which in this case is 20mm

On a few items like pins and a washer I provide dimension in inches instead of mm.

Clutch Cover Screws
Four M6 x 1.00 x 20

Clutch Cover Side Case Screws
Three M6 x 1.00 x 60
Five M6 x 1.00 x 50
One M6 x 1.00 x 40

Clutch Basket Cover Screws
Two M5 x 0.8 x 11 Countersunk Head

Shift Ratchet Pins on Shift Drum
(dimensions are in inches)
Four pins 0.475 long and 0.055 diameter with head
One pin 0.100 long and 0.055 diameter with head
Each pin has a head that is 0.106 long and 0.194 diameter

Center Case Screws
Seven M6 x 1.00 x 60
One M6 x 1.00 x 45
One M6 x 1.00 x 40

Oil Screen Cover Bolts and
Four M6 x 1.00 x 24

Small Drain Bolt on Left Center Case
One M6 x 1.00 x 8
One M6 Aluminum Crush Washer

Generator Side Cover Screws
Two M6 x 1.00 x 28
Two M6 x 1.00 x 22

Generator Stator Screws
Three M6 x 1.00 x 28

Oil Pump Screws
Four M5 x 0.8 x 18
Two M5 x 0.8 x 10

Spark Advancer Bolt
One M8 x 1.25 x 68

Timing Cover Screws
Two M5 x 0.8 x 17 Countersunk Head

Drive Sprocket Retainer Screws
Two M6 x 1.00 x 8

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 and CT200 parts available on Amazon

Honda CT90 Engine Fasteners

2019-03-06T22:02:00.003-08:00

I put this post together as reference for the length of the fasteners used in a 1972 Honda CT90 for assembling the engine cases and covers, but also for some of the fasteners used internally within the engine.

Screw size convention
Example: M6 x 1.00 x 20
M6 - is the diameter of the screw, which in this case is 6mm
1.00 - is the thread pitch of the screw in threads per millimeter
20 - is the length of the screw, which in this case is 20mm

On a few items like pins and a washer I provide dimension in inches instead of mm.

Right Side Clutch Side Cover Screws
Two M6 x 1.00 x 40
Seven M6 x 1.00 x 20

Oil Pump Fasteners
One Bolt M8 x 1.25 x 20 with a 0.118 inch diameter hole down the center that intersects a 0.040 inch diameter hole drilled radially in from the side.
Two M6 x 1.00 x 25
One M6 x 1.00 x 15
Two M5 x 0.8 0 x 10

Shift Drom Stopper Plate Screw and Pins
One M6 x 1.00 x 15 Counter Sunk Oval Head Screw
Four Pins (not shown) 0.156 inch in diameter and 0.513 inches long

Center Engine Case Screws
Nine M6 x 1.00 x 40

Left Side Case Generator Cover
One M6 x 1.00 x 45
Two M6 x 1.00 x 40
One M6 x 1.00 x 35
One M6 x 1.00 x 30
Five M6 x 1.00 x 25
One clamp for over flow line from carb

Timing Cover Screws
Three M6 x 1.00 x 12 Counter Sunk Oval Head Screws

I have seen these screws vary in length on different bikes I have worked on and while I have never seen a screw shorter then 12mm, I have seen a number of 15mm and even an 18mm long screw. There is not really much for the end of the screw to interfere withs whatever is on your bike is probably just fine. Do remember to use the small o-ring on the screw that acts as an oil seal.

Sub Transmission Cover
One M6 x 1.00 x 40
Three M6 x 1.00 x 30

If you have a later model where the cover has two guide bushings then you would need:
Two M6 x 1.00 x 40
Two M6 x 1.00 x 30

Timing Gear Cover
Three M6 x 1.00 x 12

Spark Advancer Retention Bolt and Washer
One M6 x 1.0 x 16
6mm Washer that is 0.665 inch in diameter and 0.078 inches thick

Points Plate Hold Down Screws
Two M5 x 0.8 0 x 10

Screws to hold Points Assembly to Points Plate
Two M4 x 0.70 x 5 (not shown)

Points Cover Screws
Two M5 x 0.8 0 x 18 Counter Sunk Oval Head Screws

Rocker Arm shaft Access Cover
Three M6 x 1.00 x 20

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Using a VW Lug Bolt as a Puller to Remove a Honda CT90 Generator Rotor

2019-03-04T10:43:00.000-08:00

I had read online that the wheel lug bolt from a VW had the same thread as what is in the center of the generator rotor on a Honda CT90 and makes a good tool for removing the rotor, so I thought I would give it a try.

I went on to Amazon and found a VW lug bolt and it was only $5.00, so I added it to an order I was making. The VW lug bolt has a 14 x 1.5 mm thread which is the same as what is in the inside diameter of the generator rotor that is intended to be used for the rotor removal.

I received my order from Amazon and instead of receiving just one bolt I actually received a box with 20 lug bolts, so I don't know if Amazon made an error, or that you actually get 20 lug bolts for $5.00, but in the end I now have a few extra lying around my shop.

To use the VW lug bolt to remove your CT90 generator rotor you simply thread the lug bolt into the threads at the center of your generator rotor and then restrain your crank so it cannot rotate by using your clutch holding tool or by some other means.

Then simply apply torque to the VW lug bolt and it will jack your generator rotor off of the end of the crank shaft.

The VW lug bolt worked well for me, so it you are looking for an inexpensive tool to help you remove your CT90 generator rotor you might consider giving it a try.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Troubleshooting a Honda CT90 that won't start to start

2019-02-16T23:32:00.002-08:00

Most everyone who adopts an old Honda CT90 at some point gets to where the bike won’t start and your first instinct is to start making random adjustments, but no matter how many times you adjust or clean everything the bike just won’t start. After doing this a number of times myself I now try and take a more methodical approach where I follow the sequence of steps I have outlined below, and I’m usually successful at getting the bike running again.

Others may take a different approach, but I thought I would share the items I look at and the order I look at them in case this information is useful to someone else dealing with trying to get a CT90 to start.

Step 1 – Do you have good compression?
Fundamental to getting a bike running is having a reasonable amount of compression, and the more you have the better. If you have a compression gauge put it on and see what you have, but if you have greater then 80 psi that should be adequate to start the bike.

If you don’t have a compression gauge you still can get a good sense of the level of compression you have by the amount of resistance you get when you kick the bike over. If there is a nice definite peak resistance that builds up and requires some force to get through then your probably ok.

If your bike kicks over with little resistance then your next step is to adjust your valves and hope your lack of compression is due to a misadjusted valve and not a problem with the rings on your piston. When you adjust your valves make sure you have at least .002 clearance and a hair more won’t hurt. If I don’t have a feeler gauge handy I just turn down the adjustment screw on each valve until it just kisses the top of the valve stem and then back it off 1/8 of a turn and tighten the lock nut. Based on the pitch of the thread on the adjustment screw this will give you about .0025 inch clearance.

If after adjusting your valves it seems like your compression improved then you’re on the right path to getting your bike started.

If you have faith that your valves are adjusted correctly and your piston and rings are good, but your kick starter feels kind of mushy, then there is a good chance your clutch is slipping. Slipping clutches don’t somehow heal themselves, so while it may be good enough to start your bike once in a while its only going to get worse and its time to rebuild your clutch.

Step 2 – Is your timing chain and gear installed correctly?
While this generally isn’t a problem if your bike was running previously and you haven’t disassembled your top end, but if you just picked up a new project or had just refreshed your top end it doesn’t hurt to go back and check to make sure the timing gear and chain were installed correctly.

I go into detail on how to correctly install the timing chain and gear in the post at the link below:

The Basic Sequence and Process to Set or Adjust your CT90 Timing

But the readers’ digests version is that when the crank is at Top Dead Center (and not the F fire position) like is shown in the picture below then the “O” mark on the timing gear in the head needs to be aligned with the notch in the head like is shown in the following picture.

Step 3 – Is the spark advancer assembled correctly?
Since you had to remove the spark advancer to check to see if the timing gear was installed correctly, this is the time to make sure the cam on the spark advancer is installed correctly. A very common problem is that people install the cam 180 degrees out from its correct position because the it can be installed two ways and people don’t pay attention and make sure and align the marks on the cam and base assembly when putting it back together after it may have been pulled apart to clean and lube the assembly. I show how to correctly build up the spark advancer and where the alignment marks are located the following post at the link below so you can always assemble it right the first time and avoid this problem altogether.

CT90 Spark Advancer Assembly Build-Up

Step 4 – Is the wire leading to the points assembly correctly installed so that it does not ground out to the frame of the points assembly?
There is one important design detail that is sometimes missed and that has to do with correctly attaching the wire to the points assembly so that it is electrically isolated (not touching) the metal frame of the points assembly. If assembled correctly there are three fiber washers that prevent the wire from contacting the frame.

The picture below shows all of the fiber washers along with the small bolt and nut that are used to attach the wire leading to the points assembly.

There are two large fiber washers and one small one where the small one is installed in the opening in the frame as shown below which is important in preventing the bolt from contacting the frame.

Here are all the washers installed.

And with the wire correctly attached to the points.

Another detail to look at is to make sure that the fitting at the end of the wire that attaches to the points assembly that is shown in the picture above isn't oriented so that it comes in contact with the cover when it is installed which would result in the wire always being grounded.

Step 5 – Clean, check the contact faces, and gap your points
For your points to function correctly the faces of the contacts on the points have to be flat, smooth and clean before you set the gap. If the face of the contacts look questionable then they should be filed or drag some fine emery cloth between the contacts to clean up the faces. For points to operate correctly they need to have a clean separation to ensure the field in the coil collapses quickly to produce the best spark. If there is crud/oil in and around the contacts you won’t have a clean break electrically so use some spray contact cleaner to make sure your points are nice and clean.
I have outlined the steps to gap your points in the post at the link below on the basic steps to adjust your timing.

The Basic Sequence and Process to Set or Adjust your CT90 Timing

Another thing to watch out for here is that it is possible to accidentally install the wire attached to your points so that the terminal attached to the end of the wire is rotated outwards and can come into contact with the cover when it is installed which will ground the wire and prevent the bike from starting. This can be a frustrating item because you’ll remove the cover because the points seem to be the issue, but with the cover off everything checks out fine and then you reinstall the cover and now the bike won’t start and you repeat this sequence until you hopefully figure it out. Make sure the end of the wire is tucked in nice and tight s it won’t contact the cover when it is installed.

Step 6 – Adjust your timing
With this step just set your timing and I have instructions on how to do this in a post at the link below.

The Basic Sequence and Process to Set or Adjust your CT90 Timing

The one thing to watch out for here is that sometimes with bikes that have been built up with a collection of parts from different bikes the fit between the plate the points are mounted to and the recess in the housing it rotates in when you adjust the timing, may not be a nice snug fit. If the fit is too loose then when you set the timing by rotating the plate you end up changing the gap in the points because the plate moves radially ever so slightly. This can be a frustrating problem that may not be readily apparent. In the end you usually need a new housing or plate.

Step 7 – You have a fully charged battery installed
CT90’s require power from a battery to charge the coil and produce a spark. If you have a good battery installed make sure the ground wire attached to the frame and that everything is clean at that joint so you have a nice solid ground. On the power leads from the battery make sure those connections are clean and tight and that you have a good fuse in the fuse holder.

Step 8 – Make sure you turned the ignition key to “on”
I won’t elaborate any further except to say that I have first hand experience that it can happen…

Step 9 – Ensure the spark plug cap has a good connection to the end of the spark plug wire.
One of the common areas where there can be a problem on old CT90’s is with the connection between the spark plug cap and cable. This area can see a lot of heat and sometimes the spark plug cable can become stiff and hard. If your cable is long enough, unscrew the spark plug cap from the cable and then cut off a ¼ to ½ inch of cable. Then reinstall the spark plug cap by screwing it on and you now should have a good clean and tight connection between the threaded probe in the cap with the conductive core of the cable.

Step 10 – You have a good spark verses a crappy spark
It takes a good spark to start an engine, so just because you see some sort of spark at the electrode on the plug, it may not be good enough. Sometimes a used plug with get a fine film that has contaminates that are conductive and while you see a spark its not always across the gap of the plug and won't reliably ignite the fuel mixture in the cylinder.

Whenever I have a bike that is hard starting I always put in a new plug if I have one, and in many cases it solves the problem. If you don’t have a new plug handy you can heat up the electrode end of the plug with a propane torch (and don’t be shy here) and burn off anything that shouldn't be there.

Step 11 – Upgrade your rectifier
On any CT90 I pick up one of the first things I do is upgrade the rectifier. This is an easy change to do and addresses a variety of things that can cause problems. So whether it’s a problem or not with your bike, my recommendation is up grade your rectifier, as you will be glad you did.

I have a post on how you can do this yourself and some sources if you prefer to just buy and upgraded rectifier at the following link:

CT90 Rectifier Upgrade

If you don’t want to upgrade your rectifier, but want to check to see if your current rectifier is ok, here is a link to a post I made on how to test your rectifier:

How to Test Your CT90 Rectifier

Step 12 – Checking your coil and condenser
CT90 coils are very reliable and generally are not the cause for a hard starting CT90. The plug wire leading from the coil to the plug can have issues. If you suspect your coil and or condenser may have issues they are fairly simple devices to test.

Here is a link to a post I did on how to test your coil:

Basic CT90 Ignition Coil Check

And here is a link to a post I did on how to test your condenser:

Basic Test of a CT90 Condenser

Step 13 – Checking for a spark
At this point in the process if you have checked and made sure everything in all of the previous steps was good, your CT90 should produce a spark. If you find that when you have your plug removed but plugged into the cable from the coil and touching the head, with the key on, a good battery installed and all the electric connections have been checked, that you still don’t get a spark when you kick the bike over then here is a simple way to help you isolate the problem.

Disconnect the wire coming from the points assembly where it attaches to the main wire harness and then get a length of wire that has a short length of insulation stripped from each end and then take one end and insert it into the female connector for the points on the main wire harness. Now with the key turned on like you were going to start the bike, touch the free end of the wire to the case of the engine or any other good ground for a second or two and then remove the end of the wire from where you had it grounded. The moment you remove the wire from the point where you had it grounded you should see a spark at the spark plug. If you now do get a spark that means your coil, condenser, plug wire and spark plug are all good and you have an issue somewhere within your points assembly or with the wire coming from the points being shorted out where it passes through the opening in the cylinder or the that same wire having an internal break.

If you didn’t get a spark, then there is something wrong with the coil, coil wire, condenser, or spark plug or one of the electrical connections or grounds for these items.

Step 14 – Did you turn on the fuel?
With the first 13 steps completed and you now get a good strong clean spark, but with the plug installed the engine doesn't fire its time to look at the fuel system. The first step here is to make sure you actually turned the lever on the carb to "on" or "reserve" so that fuel can get from the tank (there is gas in your tank?) to the carb.

Step 15 – Use ethanol free fuel
I have switched over to using ethanol free fuel in my bikes, especially if they will be setting unused for a period of time. I have repeated had issues with my idle jet getting gummed up when I was using fuel with 10% ethanol and had let my bikes sit for a period of time and since switching over to ethanol free fuel those problems have gone away. When you are working on a bike that is hard to start its nice to eliminate anything that could be a possible cause a problem and using ethanol free fuel helps eliminate some fuel related issues.

You can find sources of ethanol free fuel in you area at the link below:

Ethanol Free Gas

Step 16 – Are you using filters on the fuel lines coming from your gas tank?
All CT90 bikes are old, and most have had at least some issue with rust in the gas tank and the idle jet on the CT90 is so small that it takes next to nothing to clog it up which will keep the bike from starting no matter how hard and long you kick it over.

Do yourself a favor and get some in-line fuel filters, as it will eliminate problems in the future.

Step 17 – Initial carb adjustment
If you just picked up a new CT90 that doesn’t run and you don’t have much experience with the CT90 carb, the link below will take you to a post I did where I included a table with initial settings for the two screws you can adjust, so that your carb will be in the ballpark of what should allow your bike to start up.

Adjusting and Jetting a CT90 Carb

Step 18 - Are you getting gas?
The one area where CT90’s are not very robust in my opinion is with the size of idle jet used. If there is any sort of crud no matter how small, you are just about guaranteed that your idle jet will clog and prevent your bike from starting. If your hard starting issues seem to be carb related it always pays to completely disassemble the carb, clean every part and passage with a good carb cleaner like Berryman B-12 Chemtool (and try and find the non-VOC compliant if it is available in your state, its just better) and then blow out the passages with compressed air.

If your hesitant to pull your carb apart as your not sure you can get it back together, I included the link below to a post I made on how to reassemble a typical CT90 carb.

Step by Step Instructions for the Reassembly of a Basic Two Screw CT90 Carburetor

It’s always nice to get a rebuild kit when you take apart a carb so you have new gaskets, but sometimes you’ll find you can reuse the gaskets if they haven’t become too old and hard. If you’re trying to reuse your idle and main jet, but they are clogged with varnish and the carb cleaner wouldn’t clean them out, you can try using a propane torch and that will usually burn out whatever is clogging the jet.

If you do take apart your carb it’s always a good idea to recheck the float height as an incorrectly adjusted float can lead to issues caused by having too much or not enough gas in the bowl of the carb. I have instructions on how to do that adjustment in the link I shared above.

Another common cause for a CT90 to not get gas is if the vents on the gas cap of the fuel tank are clogged. What happens when this is the problem is that the bike starts just fine but after a short period of time the engine dies because gas can't flow to the carb because air isn't making it in to the gas tank and a vacuum is created that prevents the gravity feed fuel from flowing. This is not always an easy issue to catch as the bike will start fine and run for a short bit, but when it dies the rider starts to try and figure out what is wrong and during that time air seeps back in through clogged vent in the gas cap, so the next time the person tries to start the bike, it fires right up. If you think you have this problem, just loosen the gas cap so its covering the opening, but not all the way twisted down. If this solves your problem get a new gas cap or try cleaning the old one so the vent holes are clear and functioning.

Step 19 – Are you getting too much gas?
If your lucky and your bike starts just after you have rebuilt your carb, but then becomes very hard to impossible to start later on that is a potential sign that the float in you carb is cracked and leaking which will allow your bike to become flooded. This is not always easy to detect as when you take apart the carb to figure out what is wrong and the float is setting on your bench all the gas that seeped into the float will evaporate out and when you reassemble the carb your bike will start initially, but then again become hard starting. The cracks in the brass floats are not that obvious and are usually very fine hairline cracks. When in doubt just get a new float.

The other item that can cause your bike to flood is having a worn float valve. When you disassemble your carb inspect the float valve components and if you see a ring around the pointed end where it mates to the seat then it’s time to replace the float valve. These are almost always included in a carb rebuild kit, but can be bought separately.

Step 20 – Some additional comments
There is a temptation to use starting fluid to get a bike to start and I have done it myself, but in general I would recommended to avoid using it or use it very sparingly. Starting fluid has the risk of stripping out the oil film in your cylinder, which is undesirable. If you do use it and your bike starts and runs for a few seconds, that’s great because you now know that you have adequate compression, your timing is good, and you have a decent spark. Beyond that, continuing to try and get you’re bike running using starting fluid won’t fix what is keeping your bike from running and may potentially result in damage to your cylinder. If your bike starts using starting fluid, but doesn’t run otherwise you have a fuel problem and need to focus on fixing what is wrong with your carb.

Another use for starting fluid is to check for leaks between the carb and where it bolts to the intake manifold and between where the intake manifold attaches to the cylinder head. Sometimes people find they can get their bike to start with the choke on, but it dies anytime they try and remove the choke. When you use your choke it has the effect of enriching the mixture going to the cylinder. If a bike will only run with the choke on that usually means there is an air leak between the carb and cylinder head which results in an overly lean mixture without the choke on. If you suspect this condition, while the choke is on and the engine is running, spray starting fluid at each of the joints on the intake manifold and if the engine rpm’s increase it means you have an air leak at the joint where the starting fluid caused an increase in rpm’s.

If your bike can just start and idle but backfires through the carb when you give it any throttle, then that is another indication that you are running to lean and there is a good chance your main jet is partially clogged. If you close the choke and the throttle response seems to get better that is further confirmation your main jet or emulsion tube is clogged.

I hope the information I shared above is helpful in getting your hard starting CT90 back up and running.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Making a CT90 Internal Battery Bracket

2019-02-15T19:08:00.001-08:00

A common item that is missing on a lot of old Honda CT90's is the sheet metal bracket that helps cradle the battery in the opening on the side of the frame. When the battery is removed there really isn't anything retaining the bracket, so it can very easily get left out and ultimately lost.

You can sometimes find a used inner battery bracket on eBay, but lately when I have needed one I just make one as it is a very simple part and if you own a pair of tin snips and are a little bit crafty, you can make one in a few minutes.

I made the attached drawing below to help others who may be in a situation where they need a inner battery bracket and would like to fab one up, but are looking for the overall dimensions of the bracket.

The drawing does not have the dimensions for the depressions stamped into the original Honda designed bracket that add stiffness to the part, but the design on the drawing will give you a good functional part.

I hope this post was helpful and have fun making your own CT90 inner battery bracket!

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Listing of Honda CT90 Parts available on Amazon

2018-12-21T16:55:00.005-08:00

I have mixed feelings about Amazon as in some respects they are really taking over the world, but in the end they have become the simplest and quickest way for my family and I to get what we need. While Amazon may not always the cheapest place to buy things and some of their third party sellers are kind of questionable, I have generally always had a good experience purchasing item from Amazon.

Since I tend to make a lot of my purchases on Amazon, I have also started to buy much of what I need for a number of the Honda CT90 projects I am working on. While Amazon may not have many of the small unique CT90 parts like what is available on DrATV, they do have most if not all of the general parts you end up replacing on a CT90 project bike that has sat on the side of someones barn for the last twenty years.

Since it's not always easy to find things on Amazon, I decided to make a page on my blog at the link below where I have collected together a number of the CT90 related items people might use while rebuilding a bike.

List of Honda CT90 Related Items on Amazon

I plan on updating this list as I find new items related to Honda CT90's.

When you purchase really anything off of Amazon, especially form third party sellers, you really need to look at the description and make sure it will work for your particular application. So while I have provided this list of Amazon items, and I have used many of the items myself, I include this disclaimer that I am not making claim or endorsement and you really need to decide for yourself before purchasing any of these items.

There are certain items like carburetors, that I have not yet added to the list even though there are a significant number on Amazon that claim to be good fo a Honda CT90. A number of these carburetors may work on a CT90, but from my limited experience are not always a direct replacement that you can bolt on and go. When I do find one that seems like a direct replacement, I'll add it to the list.

I hope you find the list at the link above helpful.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Dynamic Timing a Honda CT90 or similar Single Cylinder Motorcycle

2018-12-18T17:15:00.000-08:00

In general, I have always statically timed the CT90's that I own and have been happy with the results. The bikes are easy to start and have good performance (assuming the plug, points, coil and wiring were all good...), but I have always wondered if dynamically timing my CT90's would make much of a difference, so I decided to dig out my dwell meter and timing light and spend some time dynamically timing one of my CT90's to see what I could learn and then share that information here in this post.

I also did an earlier post that included how to statically time a CT90 at the following link: The Basic Sequence and Process to Set or Adjust your CT90 Timing

In this post I'm also going to provide information related to adjusting your points, as the points, or more specifically setting the dwell angle, is so interrelated with engine timing that from my perspective you need to always check both anytime you feel the need to work on one or the other.

In addition to the mechanics of setting the dwell and timing, I will also dig down and share some additional insight in a few areas that are hopefully interesting and helpful to others interested in dynamically timing a CT90.
Listed below are the steps I plan on following when setting my CT90 timing dynamically:

1. Dress and clean the points

2. Set the point gap /dwell angle

3. Check the dwell angle with the dwell meter

4. Set the timing statically

5. Check the timing dynamically at idle and verify that it has not changed significantly from the static setting (ideally not more then a few degrees). If out a significant amount, adjust the timing so that dynamically at idle the pointer lines up close to the mark next to the F on the generator rotor.

6. Increase the engine RPM's to approximately 3500 RPM's and verify that the timing advances with RPM's and that the maximum advance results in the pointer being within the two advance timing marks on the generator rotor.

7. If after performing the above adjustments my CT90 runs great at idle and at speed, then I will document the dwell angle and other timing information so that the next time the bike doesn't seem to be running well or if I had to do work on the bike, I have an initial set of settings to use that worked well in the past.

To help myself better understand the different events going on within the CT90 engine I put together the chart below (you should be able to scroll to the right to see the whole chart).

From the chart above you can see that there are two basic things being accomplished when you adjust the points/set the dwell angle and then set the timing:

1. With the dwell angle you are determining the time available for current to be applied to the primary coil and allow it to reach its full potential or become saturated.

2. With the timing you are positioning the dwell period so that when it ends and the points open (which results in a spark at the spark plug) that it is at the ideal point in the stoke before top dead center.

You can also see in the chart the effect the spark advancer has on shifting/advancing the dwell period at higher RPM's. Since the fuel/air mixture in the cylinder burns a a constant rate you need to advance the point in time the spark ignites the mixture at higher RPM's so that there is enough time for the pressure in the cylinder to build up to the maximum level that coincides with the ideal point in the stroke after top dead center that will produce the greatest amount of power.

Setting the Dwell Angle
The first step in dynamically timing a CT90 is to set the dwell angle by adjusting the gap in the point assembly. Once the gap is set then the bike can be started and a dwell meter attached and with the engine running, verify that the desired dwell angle has been achieved. If not then the points can be adjusted and the process repeated until the desired dwell angle is reached.

The first time you take this approach you really won't know what dwell angle to adjust your points too, but the real benefit from using a dwell angle verses just setting the gap in your points is that once you find a point gap/dwell angle and timing setting that works well with your bike, you will be able very accurately go back and recreate that same dwell angle in the future. Using feeler gages to set the gap in your points and therefore the dwell angle, can be a very repeatable process and is generally more then adequate, but using a dwell meter gives you a direct reading of what you are really trying to accomplish.

A good practice when setting your dwell angle is to make sure the points are in good shape, flat, and clean. If there is any question, then you should dress your points with an appropriate file and clean them as well, so that they have a nice clean electrical break when they operate.

Whenever I provide a dwell angle in this post, I will refer to that angle in degrees of the "camshaft rotation" which is actually half the angle of rotation of the main crankshaft due to the gear driving the timing chain on the crank only having half the teeth of the timing gear that is driving the camshaft.

To measure the actual dwell angle I used an old Craftsman Engine Analyzer I own that includes a dwell meter. The picture below is of the meter setting on the rear rack of the bike connected to my CT90. I used a 12 volt battery charger to power the dwell meter and one detail you need to be aware of when taking this approach is that you need to ground the negative lead of the meter and battery charger to the CT90 for the meter to work correctly.

The only other connection from the meter to the CT90 is with the one lead that needs to be connected to the lead from the ignition coil to the points which I just connected as shown in the picture below.

The only issue with using this meter on my CT90 is that it only has a scale for 8, 6, and 4 cylinder engines and nothing for a single cylinder engine like my CT90. This ends up only being a minor issue as you can use the reading from the 8, 6, or 4 cylinder scales with a little math to get to a correct reading for a single cylinder CT90.

To convert the dwell angle measured on a CT90 using a meter for a multi cylinder engine, you would multiple the indicated reading from the meter by the ratio of the degrees of distributor cam rotation required to fire a single cylinder one time between the CT90 and the multi-cylinder engine scale you were using from the meter.

For a CT90 the overhead cam directly drives the cam lobe that actuates the points assembly and it requires 360 degrees of cam rotation to fire the spark plug one time. For an 8 cylinder engine the distributor cam only has to rotate 45 degrees to fire each spark plug compared to 60 degrees and 90 degrees on a 6 cylinder and 4 cylinder engine respectively.

Example for 8 cylinders engine: CT90 Dwell Angle = 360/45 * reading from meter for 8 cylinder
Example for 6 cylinders engine: CT90 Dwell Angle = 360/60 * reading from meter for 6 cylinder
Example for 4 cylinders engine: CT90 Dwell Angle = 360/90 * reading from meter for 4 cylinder

The resulting CT90 dwell angles from the examples above would be in degrees of the overhead cam. To convert the dwell angle that is in degrees of the cam rotation to degrees of the crank rotation you would simply multiply by two.

For example if you used the eight cylinder scale on a dwell meter connected to your CT90 and the reading was nine degrees, then the dwell angle in terms of CT90 cam rotation would be equal to 9 x (360/45) = 72 degrees. In terms of CT90 crank rotation it would be 2 x 72 = 144 degrees.

From the Honda CT90 manual, the recommended point gap setting is .012 to .016 inches. I wanted to know what the corresponding dwell angle would be for each of the end values from the Honda recommended range, so I first set the points to .012 inches and then recorded the dwell angle and then I set the points to .016 inches and also recorded the dwell angle.

Here are the results for my CT90:

Given that the Honda manual states an acceptable range for your point gap to be within, you may ask yourself why should I care what my point gap is as long as it is within the recommended range? The short answer is that for the most part it probably doesn't make much of a difference, but it is good to understand how the point gap and resulting dwell angle impact the charging of your coil.

I put together the following chart to show the relationship between the time available to charge/saturate your coil verses engine RPM's for both the minimum and maximum dwell angles.

For a typical ignition coil it takes about .0030 to .0035 seconds to fully charge/saturate the primary coil and that is reflected by the green horizontal line on the lower portion of the above chart. The blue and red curves reflect the time the points are closed for the minimum and maximum dwell angles through the full range of RPM's that a CT90 engine would typically operate at.

At lower RPM's the gap above the green line but below the blue and red lines represents the excess amount of time beyond where the coil is already fully charged where the points are still closed and current is still being applied to the coil unnecessarily and potentially can lead to heating of the coil. While coil heating can be an issue in some automotive applications, I have never heard of any CT90 coils being damaged in this way, so it really isn't a concern.

Where the chart gets interesting is out around 5800 RPM's as the blue minimum dwell curve starts to fall below the green line which indicates that the points will not be closed long enough to fully charge the coil which could lead to a weak spark at the plug that will get progressively weaker as the engine RPM's continue to increase. With the maximum dwell angle (smallest point gap) this does not become an issue until you get out around 8000 RPM's.

If you have a CT90 that tends to mis at high RPM's one of the first things you may want to consider is adjusting your point gap and shift it towards the minimum so that you will have the maximum dwell angle and therefore be fully charging your coil throughout most of the RPM range of the engine.

Based on what I have learned in trying to fully understand the CT90 ignition system, I tend to always gap my points at the minimum and if I have time to spare I'll pull out my dwell meter and check to make sure my dwell angle is around 72 degrees of the cam angle or 18 degrees using the 4 cylinder scale on my dwell meter.

With the dwell angle fully understood and set, we will now turn our attention to adjusting the timing.

Adjusting a CT90 Timing Both Statically and Dynamically
In a previous post here at this link I went into detail on how to statically time a CT90, so I won't repeat that information again here.

Before we get into the steps to dynamically time your CT90 I think it's important to review the basic features of the points plate involved with adjusting your timing and also the timing marks utilized on the generator rotor.

The following is a picture of the points plate with the features labeled that are used in the timing process.

The following three photos are of the generator rotor and have labeled comments on the significant markings associated with the timing process.

We still need three more things before we can dynamically time our CT90 and they would be an RPM meter, a timing light, and most importantly a clean working spark advancer with good springs.

What I used to display RPM's was an inexpensive Tach and Hour meter I picked up on Amazon. The meter is pretty basic and only updates every half a second or second, but it is more then adequate for use in dynamically timing my CT90. Here is a link to the meter at Amazon in case you are interested.

The way the meter picks up the spark plug firings is by wrapping the end of the wire coming from the meter five or six times around the spark plug wire and then securing it like is shown in the picture below.

For a timing light I just used a Craftsman timing light that I have owned for over 40 years powered by a battery charger. In the end the battery charger would not power the timing light more then for a short period of time, so I had to end up powering it off of a normal car battery.

Last but not least is that if you plan on dynamically timing your CT90 with a timing light your spark advancer really needs to have a good set of springs. If the springs in your spark advancer are weak, then your spark advancer may already be advancing your spark by a significant amount at idle. If you hook up your timing light and adjust your timing to back out the advance due to your weak springs by retarding you timing significantly at idle, you'll just end up making your CT90 hard to start because the timing will be way too retarded.

The CT90 I used for this post had a spark advancer with weak springs and I'll go into how I corrected that issue below.

With all the pieces in place the next step is to go through dynamically timing your CT90.

Here are the steps:
1. Statically time the CT90

2. Start the bike and with it idling at approximately 1300 RPM's, verify with a timing light that the line/mark next to the "F" on the generator rotor lines up with the fixed timing pointer.

3. If the line/mark next to the "F" does not line up then rotate the points plate to advance or retard the timing so that the line/mark does line up with the pointer.

4. Next increase the RPM's on the bike up to approximately 3500 RPM's and verify the timing pointer is pointing somewhere between the two advance timing lines on the generator rotor.

5. If the pointer at 3500 RPM's end up pointing somewhere beyond the line/mark next to the "F" but short of the two advance timing line/marks, then the spark advancer should be removed and inspected to make sure it is clean and operates freely.

The actual Test
With the CT90 I am using to make this post, I found that when I checked the initial timing at idle with a timing light it showed the timing advanced by 8 to 10 degrees. I know I wasn't 10 degrees off when I set the timing statically, so I suspected that the springs on my spark advancer were weak, but to see what would happen I retarded the timing to bring back the mark next to the F to be in line with the timing pointer dynamically. After making this adjustment the bike became very hard to start, so to do this right I knew I needed to go in and tune the springs on my spark advancer to make sure that the advancer was not adding any advance at idle.

My first attempt to correct the significant amount of advance I was seeing at idle was to remove the spark advancer and check and document the length of each spring and then using needle nose pliers, I was able to shorten the overall length of each spring buy tightening up the curl/hook at each end. Using this technique I was able to reduce the length of each spring by approximately 0.040 inches. I didn't put much thought into how much I would shorten the springs and just tried to get the maximum amount I could and still install the springs back on the advancer.

Spring #2 - Length 0.862 before adjustment

Spring #2 - Length 0.821 after adjustment

Following this shotgun approach to fix the issue I was only partially successful. While I fixed the issue of having 8 to 10 degrees of advance at idle, I completely failed in that I had shortened the springs so much that the spark advancer didn't increase the advance to any degree no matter what RPM I increased the engine too. So it was back to the drawing board to put a little more thought into how I needed to approach fixing this issue.

For my next attempt to fix this issue and get the springs on my spark advancer turned to be "just right", I decided to adjust each spring so that I would have the exact same amount of preload or stretch at the idle position where the cams weights on the spark advancer are fully retracted.

To obtain the exact same amount of preload or stretch in each spring, I needed to know what the dimensions were of all the features used to retain the springs in each position on the spark advancer. Using a set of calipers and a drill as shown in the picture below, I took measurements of all the various features on the spark advancer and the diameter of the spring wire and I was able to calculate the baseline length of each spring interface on the advancer (they are different).

Since I had documented what the original length was of each spring before I took my shotgun approach, I was able to back calculate how much baseline stretch/preload I had in each spring and it was 0.018 in Spring #1 and 0.013 in spring #2. The initial stretch/preload while not enough, was close to being acceptable, so I decided to adjust the length of each spring so that there would be 0.020 of initial stretch/preload and reinstall the modified spark advancer in my CT90 and see if it got me what I was looking for.

The 0.020 of initial stretch/preload worked out to be just what was needed and only a minor timing adjustment was required from the static setting to when it was checked with a timing light at idle. The spark advancer also advanced as expected up to 3500 RPM's where the pointer ended up between the two marks on the generator rotor.

Here is a short video showing the static timing setting and then after all the final adjustments had been made, showing the timing being checked with a timing light at idle and at higher RPM's showing how the timing advances with engine RPM's.

I have also included the table below to clarify all of the steps I went through to dial in the tuning of the springs on the spark advancer with the final spring lengths shown in red below (you should be able to scroll to the right to see the whole chart).

Summary
I hope the information I shared in this post is interesting and useful to others working on their CT90's. For myself, while I will always agree that dynamically timing your CT90 is the ideal approach, I will most likely still just statically time my CT90's and call it good. I didn't notice much if any change in performance on this CT90 that I dynamically timed, so I doubt I will go to all the trouble on my other bikes. I will take the time in the future to ensure that the springs on my spark advancers have approximately 0.020 initial stretch/preload to minimize any advance being added at idle. The CT90 does not have a sophisticated advance curve, and kicks in most of the timing advance at relatively low RPM's, so if your spark advancer is working correctly and you have good springs, I think statically timing your CT90 will give you more then adequate performance.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Product Review - Audew Multi-Function Jump Starter

2018-11-30T15:08:00.003-08:00

Product Review - Audew Multi-Function Jump Starter

This is a review of a small lightweight multi-function jump starter and portable power source made by Audew. While not directly related to Honda CT90's, this is a handy device to have available to start a dead battery in your primary vehicle or charge up your cell phone or other USB powered devices while out on a remote backcountry ride on your CT90.

The Audew multi-function Jump Starter is available at Amazon here at this link.

I want to acknowledge upfront that I received this multi-function jump starter from the manufacture in exchange for doing this review. The link to Audew's website is here in case you were interested in other products from Audew.

The Audew Jump Starter comes with everything shown in the picture above which includes:

The primary battery pack
The intelligent jumper cable assembly
A USB type C to USB type C cable
A USB type C to USB type B ( what were all used to) cable
A carrying case
Instructions

It is worth pointing out that nothing is included to be able to charge the unit from a normal wall electrical outlet, so you have to provide a USB charging block or charge the unit off a USB port on your computer.

The basic unit of the Audew Jump Starter is a battery pack that has five sockets/outlets/ports to support a variety of functions along with a flashlight and a battery leveled indicator.

On one end of the unit there is the flashlight, a USB Type C port and two standard USB ports.

The Type C port is the port used to charge the unit using either one of the two supplied cables and your own power source. This port can also be used to power devices if so desired.

The middle port is a standard USB port and is rated at 5V and 2.4Amps so it could be used for charging a tablet or smart phone or other devices within the indicated power range.

The third port is a standard USB port and is rated for 5v, 9V, or 12V and no current level is provided.

I hooked up my iPhone to each of the standard USB ports and the phone was charging normally.

The LED flashlight is controlled by the power button on the face of the unit and is initially turned on by holding down the button until the light comes on and this point it will be a solid light. If you press the power button again the flashlight will go into a strobe mode and if you press the power button one more time it will blink a SOS signal. The forth time you press the power button the flashlight will turn off.

On the left side of the unit there is a 15v, 10Amp power outlet that can be used to power a variety of devices.

On the right side of the unit is the plug that accepts the intelligent jumper cables that are included.

The plug socket is designed so that you can only install the jumper cables one way.

The intelligent jumper cables are a single assembly that consists of a modular plug that plugs into the battery pack and a red and black jumper cable clamp that is attached to the modular plug with about ten inches of cable.

The modular plug on the intelligent jumper cables is a key component in the system as it contains two indicator lights and a "boost" button that are important elements when you use the Audew Jump Starter to start you vehicle.

When you plug the intelligent jumper cables into the battery pack the battery charge level lights will automatically come on indicating the level of power remaining in the unit.

Test of its primary function - Can it start a vehicle

I fully charged the Audew jump starter and then packed it away in its case for well over three weeks before attempting to use it to start my 2000 Ford Ranger to simulate the jump starter being left in your trunk for an extended period before running into a situation where you find yourself with a dead battery and in need of a jump.

When I pulled out the Audew jump starter after letting it set for several weeks I first hit the charge indicator button to see if the jump starter was still charged up and all four blue lights lit up indicating it was still charged up, so it passes its first test in that it demonstrated it can hold a charge.

I next connected the jump starter to to the battery in my truck with the red clamp attached to the positive post and the black clamp attached to the negative post as shown in the picture below.

With everything hooked up correctly I looked at the indicator lights on the side of the Cable indicator and the green light was on as it is supposed to be, but the red light was also on which I am not for sure is correct or not.

I then incorrectly hooked up the jump starter by connecting the red clamp to the negative post and the black clamp to the positive post and the unit immediately began making a loud high pitched sound and the red light on the side of the cable indicator turned bright red indicating that the jump starter was incorrectly hooked up. Once I disconnected one of the clamps the sound stopped. I never did hear a buzzing as indicated in the instructions, but I assume the high pitched sound I heard was what is consider the "buzzing" in the instructions.

Since the battery in my truck is good, I disconnected the negative lead to my battery to simulate a completely dead battery and then correctly hooked up the jump starter with the black clamp connected to the negative battery cable and the red clamp to positive cable. Using my finger I pushed the boost button on the side of the cable indicator as indicated in the instructions.

I then tried to start my truck and absolutely nothing happened.

I then went back and this time used the tip of one of my keys to press the boost button as I wasn't sure that it really was pressed when I used my finger. I then went back and tried to start my truck and when I turned my key to the fist position the radio came on which was a good sign and then I turned the key further the engine started right up, so the jump start worked as indicated and the engine turned over at the same speed as when it was hooked up to the actual battery.

I made the following video so that you can hear the sound the unit makes when it is hooked up incorrectly and also see it start my truck. I'm pretty impressed that this jump starter really has the power to turn over the engine in my truck.

As a follow-up test I wanted to see how many times a fully charged Audew Jump Starter could start my truck so I left it charge overnight plugged into my USB charger and it was fully charged in the morning.

I then took it out and set up the test the same way I did in the video I shared above by disconnecting the negative cable from my battery and then connected the Audew Jump Starter to the negative battery cable from my truck and the positive post on the battery which still had the battery cable connected.

Using the Audew Jump Starter I was able to start my truck a total of 26 times which is pretty impressive. In-between each starting I would have to wait until the until the green "correct light" was solid before I would be able to press the "boost" button so I could start my truck again. At the 24th time I started my truck the Audew Jump Stater started to make a loud tone like the tone when the unit was hooked up incorrectly and the tone would be a repeating set of three loud tones which I took as a low power warning as there was only one bar left on the battery charge indicator. I was only able to start my truck two more times with the warning tone continuing through those last two tests of starting my truck. I didn't want to damage the Audew Jump Starter so I stopped trying to start my truck after 26 successful starts using the Audew Jump Starter. I should point out that in the documentation included with the unit, that Audew recommends not doing more then 3 attempts at starting a vehicle before allowing the unit to rest for a couple of minutes before trying again to prevent damaging the unit due to potential overheating. During the test I preformed I only waited long enough for the unit to rest before starting my truck again, so the test I did was pretty severe.

Overall I found the Audew Jump Starter to do everything that it claims it can do and I find it pretty impressive that a device as small and light as the Audew Jump Starter actually has the power to start a car.

This is something that I will end up keeping in my car.

The Audew Jump Starter is available at Amazon here at this link.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Harbor Freight/Haul Master Motorcycle Carrier for use with a CT90

2018-10-15T10:23:00.002-07:00

Product Review - Harbor Freight/Haul Master Motorcycle Carrier use with a CT90

A few months ago I picked up a Haul Master motorcycle carrier from Harbor freight to use to haul around CT90's that I own. The carrier normally sells for $124.99, but it was a holiday weekend when I bought the carrier and Harbor Freight had a special 25% off coupon so the cost was very close to $100.00 out the door which I though was a pretty good deal.

The carrier does require some assembly, but went together easily and I didn't have any issues with mating it up with the Curt 2" receiver hitch on the back of my Subaru Outback that I will use most of the time to haul around my CT90's.

Here is a picture of the carrier alone mounted to the back of my Subaru.

The carrier does include a nice anti-rattle feature that consists of a couple of bent plates that are retained by a through bolt that capture the end of the receiver hitch as shown in the picture below.

I have seen where people have installed the bent plates with rotated 180 degrees from how I have shown it above (and that is probably the right way to do it :-) ), but either way the anti-rattle feature is very effective and prevents any unwanted motion of the carrier relative to the receiver from occurring as your driving down the road.

The ramp that is included with the carrier works well and simply hooks on either end of the carrier to load or unload your bike.

One element of the Haul Master carrier design that works out great with CT90's is that when you first roll the bike up onto the carrier and the front wheel drops down in its intended location, the kickstand perfectly lines up with the center square tube on the carrier so you can actually use it to hold the bike up before you install the first tie down straps.

The design to retain the front wheel of your bike to the carrier works well and consists of a clamping systems that captures the tire and rim and then a pin that is inserted through the spokes to help retain the bike to the carrier when all your tie-down straps fail and everything goes to hell and a hand basket.

Here is a picture with the front wheel fully installed in the carrier.

There is a similar feature on the carrier that is designed for the rear wheel of a bike to drop down into so a pin can be installed through the spokes like on the from wheel, but due to the short wheelbase of the CT90 rear wheel does not drop into the feature so the cross pins just serve as something for the wheels to roll over when loading or unloading the bike.

There are four holes provided on the carrier for connecting your tie down straps that do the job. Two are on the square tube at the end of the carrier that slides in your hitch.

And two in the plate at the end of the carrier used for clamping up the ramp in its storage location.

The picture above also shows how the ramp is retained in its stowed position by a spring loaded plate secured by a wing nut and also the large knob on the end that clamps the ramp up against the main structure of the carrier. The systems seems to work well as I have not had the ramp come loose while using the carrier.

Here are two pictures showing one of my CT90's secured to the Harbor Freight Haul Master Motorcycle carrier.

Overall I think the Haul Master Motorcycle Carrier sold by Harbor Freight works great for hauling around your CT90 and is a great deal for the money.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Shop Amazon Warehouse Deals - Deep Discounts on Open-box and Used Tools & Home Improvement

Making a Transparent Timing Cover for your CT90

2018-10-09T16:20:00.001-07:00

I was working on a post about dynamically timing CT90's recently and decided to make a clear plastic cover like the one in the picture below so that I could view the timing marks while the engine was running and not have to worry about the small amount of oil that splashes out.

To simplify the overall effort I went on Amazon to see if I could find a clear plastic disc that was the same or very close to the diameter of the generator access cover and found the disc here at this link on Amazon.

The disc is made from Acrylic and was 5.0 inches in diameter and a 1/4 inch thick. At the time I purchased the disc it was only $8.75 with free Prime shipping, but when I checked recently the price was now $11.85 for the Prime option.

The 5.0 inch disc is slightly smaller then the side cover it is meant to replace, but is still large enough to have plenty of room to drill the holes needed to mount the disc to the CT90 engine. The disc I received was delivered with a nice protective paper cover on each of the two faces which will protect the disc while drilling the holes in it.

To drill the holes in the disc I simply used the side cover as a a guide and centered the disc on the back of the cover and then placed them both in a vice to hold them together while I drilled the holes.

I used a 1/4 inch diameter drill bit that is just the right size for the 6 mm screws I used to mount the cover to the engine.

With the holes drilled, I just peeled off the protective paper and had my finished transparent cover.

To mount the transparent cover I just used some short 6 mm pan head screws like are used elsewhere on the CT90 and a standard gasket.

While not a necessity, the transparent cover is nice to have and it makes it easy to use a timing light without having too much of a oily mess to clean up afterwards. If you are thinking about making this cover here is the link to purchase the disc on Amazon.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon

Product Review - Audew 150 psi Heavy Duty Double Cylinder Air Compressor

2018-09-17T21:19:00.000-07:00

Product Review - Audew 150 psi Heavy Duty Double Cylinder Air Compressor

This is a review of a small portable 12 volt air compressor that is unique in that it is configured with a single motor that drives a piston and cylinder located at each end of the motor to where the combined output for the two cylinders is up to 150 psi. While not directly related to Honda CT90's, a compressor like this is a handy device to have available if you take your CT90 out camping, Hunting, etc. and need to top off your tires with air.

I want to acknowledge upfront that I received this compressor from the manufacture in exchange for doing this review.

I have structured the review of this compressor from Audew into four sections:

1. The basic compressor and what is included
2. How does it perform
3. Summary and recommendation

The Basic Compressor and What is Included
The compressor from Audew retails for $59.99 at the time this review was written and is available from Amazon and can be viewed here at the Audew website that also contains a link to the Amazon page where the compressor is sold.

The compressor comes packaged in the box shown below and is well protected by the Styrofoam blocks within the overall package.

The artwork/pictures on the outside of the box my compressor was delivered in are of a slightly different configuration compressor, but the box does indicate four different part numbers in the lower right hand corner so I assume that this compressor is one of those numbers. The internet link I provided above is for this specific compressor that I am reviewing.

Within the box the following items are included:

1. The compressor
2. A yellow coiled air hose
3. An electrical adapter that allows you to connect the compressor power cord directly to a car battery
4. Three air hose end adapter that allow you to fill air mattresses and sports balls
5. A baggie that contains basic instructions and a spare fuse and spring
6. A carrying case you can use to store the compressor and included accessories

For this price range, the compressor seems like a well built unit as are the accessories which all are of acceptable quality.

The basic compressor is approximately 10" long, 6" tall, and 4" wide and weighs 5.5 lbs with all of the accessories that are included.

The compressor is actually an integral assembly that has the following features:

1. Basic compressor unit
2. An integral pressure gage that goes up to 150 psi
3. An 12" air hose with a rotating collar at the end which contains a female thread 0.305" x 32 TPI (typical Schrader valve thread specifications)
4. A 9.5' long power cord that has a plug on the end that can be inserted into a typical cigarette lighter
5. A rocker style switch on the left side of the compressor housing as you are looking at the integral LED light that is the on/off switch for the compressor
6. A five element LED light at one end of the compressor housing that has an on/off switch located on the right side of the compressor housing
7. A folding carving handle on the top of the assembly
8. Four rubber feet on the bottom of the compressor assembly

The following is a picture of the pressure gage that goes up to 150 psi (lb/in^2), but is also scaled in kg/cm^2 and kPA (BAR) for those of you who like to read pressure in scales other then psi.

The connector at end of the power cord is of a typical design that can plug into a cigarette lighter (which very few cars come with now days...).

And the fuse for the compressor is actually contained within this plug. The fuse is a 30 amp and a spare fuse and spring that is part of the plug assembly are also included in the accessories that came with the compressor.

As stated earlier, the air hose that is permanently attached to the compressor has a collar with a female thread that is the same thread pitch as is used on a typical Schrader tire valve stem. The collar also has internal features like what you would see on a bicycle pump or air hose at a gas station that allow the end of the hose to be attached to a Schrader valve stem and depress the inner plunger and seal the connection so a tire can be inflated.

The end of the yellow coiled air has is also shown in the picture below as it has the same features as the short air hose on the compressor.

The following picture is of the integral LED light. It should be noted that the LED light is powered by the power coming to the compressor through the power cord, so if the cord is not connected the light cannot be powered.

The last feature is the fold out carrying handle that is simple and functional.

The coiled air hose is a simple configuration where on one end there is a threaded collar like what was described earlier on the short air hose on the compressor and on the other end has a male threaded end that is also the same thread as is used on a Schrader valve.

An electrical adapter is also included that allows the power cord to be attached to a typical car battery. The battery clamps on the connector are also marked with a positive (+) and negative (-) sign for those who may not know that the red clamp hose to positive and black goes to negative.

Three small adapters that can be threaded into the end of either air hoses are included where the adapter in the middle of the photo below can be used to inflate sports balls and the other two adapters can be used to inflate air mattresses and similar products.

The carrying case included with the compressor is pretty basic and is basically a nylon bag with a single zipper and two webbing handles. The bag easily holds the compressor and the included accessories so that you can store it in the trunk of your car or behind the seat in your truck.

How Does It Perform
In general, the Audew compressor does what it is intended to do without and major issues.

For my initial testing of the compressor, I used a 15 amp battery charger I have so I could run the compressor on my bench. The first thing I noticed that is that when running the compressor unloaded without it connected to any item where pressure would build up, the compressor was pulling about 10 amps as indicated by the meter on my battery charger.

When I hooked up the compressor so that it was providing air at a lower pressure around 20 to 30 psi, the current draw went up to around 15 amps. Given the current draw, which is not unexpected for an electric compressor, was beyond the limits of my battery charger I decided to do any remaining testing with the compressor hooked directly to the battery of a car I had in my garage at the time

When you do connect the power cord to a power source using the basic connector or the adapter provided, there is a red indicator light on the power cord connector as shown in the picture below that lets you know that there is power going to the compressor.

I used the compressor to fill up a car and then one of the tires on one of my CT90 project bikes and the compressor performed as expected and easily filled the tires in a reasonable period of time.

The only real issue I had is that when using the threaded end of the air hose to attach to the of the valve stem on the tire s that when you go to remove the air hose you end up loosing some air pressure while you are unscrewing the end of the hose from the valve stem. On a car tire this isn't and issue, but on my CT90 the pressure in the tire would drop by 5 psi minimum, so when filling a motorcycle tire you would need to overshoot the pressure you wanted to hopefully end up being ok after you removed the air hose. It would have been nice if Audew could have included a quick disconnect style of attachment for tire valve stems so this would be less of an issue.

The attachments provided to use to fill air mattresses and sports balls, worked as intended and the compressor didn't seem to have any issues running in an unloaded condition due to the low pressures required to fill these sort of items.

The coiled air hose provided worked fine and while it is stated that it is 5 meters in length (and I don't doubt that totaled coiled hose is 5 meters) it really can only be usefully stretched about 6 to 8 feet when using the hose.

The pressure gage on the Audew compressor seemed accurate. When I would fill a tire using the gage on the compressor and then check the pressure in the tire afterwards with a hand held gage I have the pressure would read the same.

I wanted to test to see if the compressor could actually put out 150 psi, but I really didn't have anything to inflate to that pressure so what I ended up doing is making a plug for the end of the hose and my plan was to then just turn on the compressor and see if the gage on the compressor would reach up to 150 psi.

For a plug, I ended up taking the one adapter for inflating sports balls and filled the center with epoxy as shown in the picture below.

I assembled the plugged adapter into the end of the yellow coiled hose and then connected the coiled hose to the short hose on the compressor. This way I would be able to test to see if the compressor could reach 150 psi and also if the yellow coiled hose could hold that same pressure.

When I turned on the compressor to do the test, the pressure on the gage increased until it reached 150 psi and then I shut off the compressor. The compressor didn't have any issue reaching 150 psi and the yellow coiled hose held the pressure without any issues.

I made a short video below showing the test, so you can have an idea of how the compressor sounds while operating both without the plug and with the plug.

Summary and Recommendation
Overall the Audew compressor performs well as do all of the accessories provided with the compressor. The compressor can truly get to 150 psi which is great if you have an application needing that high of pressure, but you need to be aware that the compressor does draw from 10 to 25 amps depending on the pressure being provided, so it is advisable to keep your car running while the compressor is connected to your battery to prevent it from being drawn down.

The only real improvement that Audew should consider with this compressor is with providing a quick release style fitting/accessory for attaching to Schrader style tire valve stems so that minimal pressure is lost when disconnecting the hose from the valve stem.

The Audew compressor would be a good choice if you are looking for a small 12 volt compressor to keep in the trunk of your car or in your camp if you need a compressor to top off you CT90 tires while out hunting or trail ridding.

Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)

Link to page with listing of CT90 parts available on Amazon