CT90 Restoration Adventures

 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

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. 

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

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 wh

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.

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 ca

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

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

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.

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 compressi

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 pe

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...), b ut 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

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.

I had a cylinder head where the threads for the spark plug hole had stripped out and needed to be repaired and I decided to use a Time-Sert to repair the treads.  This was my first time using a Time-Sort so I decided to do a post here to share the process that you go through and what the final installed insert looks like.  I have used Helicoil's in the past to repair damaged threads on other bikes I have owned so I first started to look for a Helicoil repair kit and the ones I found were around $48.00 dollars which sounded high and while I find Helicoil's fine for most repairs, for a spark plug hole they are not really idea in my opinion as you'll be removing the spark plug on a regular basis and I would prefer something more robust and permanent. In digging around on the internet I came across Time-Sert thread repair kits that use a very robust looking insert which I liked, but I was shocked at the price of the kits where the cheapest I could find was still around $88.0

I have one 1971 CT90 where I was going to rebuild the clutch because the kickstarter just wasn't turning over the engine like it used too,  and I also had a Big Bore kit from DrATV that I wanted to install. My intent was to just do the top end and rebuild the clutch with new disks, but when I opened up the cases to rebuild the clutch pack I found a slick black slime in the bottom of the case.  I didn't like the idea that there could be black slime in the rest of the engine, so I decided to disassemble the entire engine to make sure I cleaned everything out.  Since I was tearing everything apart I thought I would document step by step how everything goes back together in this post in case others were interested in knowing what the inner workings of a CT90 engine look like. Links to Related Posts: My Honda CT90 Clutch and Headset Nut Tool Cut Away of a CT90 Engine - CT90 Engine Exposed! Repairing Damaged CT90 Spark Plug Threads Using a Time-Sert Thread Insert CT90 Clutch P

All CT90's at some point in their life will have the clutch start to slip and require the clutch assembly to be rebuilt. Links to Related Posts: CT90 Engine Reassembly Making a Low Cost Clutch Holding Tool for Your CT90 Shift Drum Stopper Replacement When Doing a Clutch Rebuild I have one CT90 where I could tell the clutch was starting to slip because the kickstarter just wasn't turning over the engine like it used too, so I decided to rebuild the clutch.  I don't normally tear the whole clutch pack apart when I install new clutch disks, but when I opened up the cases on this bike I found a slick black slime everywhere, so I decided to disassemble the entire clutch assembly (and actually the rest of the engine...) to make sure I cleaned everything out.  Since I was tearing everything apart I thought I would document how everything goes back together in this post in case others were interested in knowing what the inner parts of the clutch pack look like. I have als

I am in the middle of adding a DrATV Big Bore Kit to my 1971 Honda CT90 and when I pulled and disassembled the head both the exhaust and intake valve had a pretty significant groove around the area where the valve seats.  The bike was running fine before I pulled it apart, so I could have just cleaned everything back up and used the old valves, but since I had it apart I figured I would replace the valves if I could find a set that wasn't too expensive. I spent some time on eBay and kept seeing sets of valves made by Shindy with a part number of #07-002.  The funny thing was when the ad on eBay was for a CT90 the price was around $19.00, but I noticed the same set of valves being sold for Honda ATC's with no mention of CT90 and the price was only $13.55 with free shipping from within the USA which I thought was a great deal. I ended up ordering the valves from eBay seller parts_giant and in a few days the parts showed up in my mailbox.  You can also get this set of valves

I am in the process of installing a DrATV Big Bore kit on a 1971 CT90 that I own and I am also replacing the clutch disks at the same time, so since I was into the engine that far I figured I'd pull the other side cases and clean them up and paint all three side case that came originally painted from Honda. This is the first time I have painted the side cases on one of my motorcycles, so I spent a little time searching the web to see what other people were doing as far as what paint to use. T settled on using the self etching primer and paint color shown in the picture below.

I was working in my shop the other day prepping some side cases for paint from one of my CT90's and noticed the "PAT. APPLN. PEND" that is cast into the side of one of the cases just above the high/low range gearbox and selector and I started wondering what if anything, Honda had actually patented on the CT90.

In this post I want to share a very simple and inexpensive way to build a clutch holding tool with plumbers tape. Update: I now make and sell a clutch holding tool that also can be used to loosen your headset nuts and more info is available here at a post I made at this link . There is a good chance with every Honda CT90 that at some point in its life you are going to have to rebuild the clutch.  Rebuilding your clutch isn't really all that difficult of a task to do, and it has the added benefit of allowing you access to clean your oil screen and also to check to make sure your shift drum stopper hasn't developed any cracks (see: Shift Drum Stopper Replacement When Doing a Clutch Rebuild ) While the overall effort to replace your clutch disks is very straight forward, there are two steps in the process that can be a bit of a pain if you don't have the right tools.  The challenging steps are with finding a way to hold the clutch assembly and keep it from rotating wh