CT90 Restoration Adventures

As of 4/4/2022 I have decided that I will no longer make these clutch holding tools.  I have  provided a file of my design that would enable you to make you own copy of the tool here at this link . 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.  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...

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.

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...

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...

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 ha...