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Honda CT90 Engine Reassembly

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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

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

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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. Related Posts: A New Batch of Honda CT90 and CT200 3D Printed Parts 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 wir

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

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 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 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.

More 3D Printed Honda CT90 Part Designs

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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.

A 3D Printed CT90 Valve Spring Compression Tool

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 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 Printed CT90 K1 Rear Airbox Snorkel

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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

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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 ha

Aftermarket Honda CT90 Carburetor Drain Modification

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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. Related Posts: Adjusting and Jetting a Honda CT90 Carburetor  Here is a picture with the old carb on the left and the new carb on the right.