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 Cl...

Buying a CT90


General Thoughts - Updated 1/10/19
When buying a CT90 you need to decide beforehand what you are really looking for with respect to do you want a project to work on or do you want a fully restored bike that starts first kick. There are no hard and fast rules with the price you should expect to pay as it varies widely and a lot of the time the price may be driven by what someone has put into the bike while they have owned it. Below I'll provide you my opinion on what you might pay for bikes in various conditions and also some of the dealsI have come across and what I look for when I am buying bikes for a new project. In general I have found that older CT200's or CT90's without the dual range transmission will go for less than CT90's with telescoping front forks and a dual range transmission. The older CT200's with a pushrod engine are a fun bike to work on, but parts are not as readily available, so if you do go down that path be aware it will be a little more of a challenge, but that may be just what you were looking for.


Part Bikes Without a Motor
If your trying to bring a CT90 back to life one of the best ways to get pats is to buy an incomplete bike that is usually missing the motor and maybe several other components. These parts bikes are great for picking up various fasteners, a tank or seat, maybe a rear rack, etc. and I have been very successful at getting a bike with two wheels and a frame and a variety of other parts for around $50.00.



Non-Running Basket Case Bike with Motor
I have been able to get bikes that are about 90% complete and have been sitting out in the weather with a motor for as low as $100.00 and try not to pay more than $150.00. Whit these bikes the cylinder is almost guaranteed to be rusty and need a new piston and bore and gasket set which will be around $110.00, so you will quickly be into the bike for a few hundred dollars before its running, so its important not to pay to much up front. I have paid around $300.00 for several bikes where they were complete, but partially disassembled, but had been stored indoors and everything was in good shape including the bores and it generally didn't take much to get these bikes running. I did see one nice complete bike on Craigslist that had a title and the guy was only asking $35.00 for it on Seattle Craigslist, but it was gone within minutes, so if you are patient and stay on top of Craigslist you'll eventually find a great deal.
A Basic Running Bike 
If you are just looking for a CT90 that runs, shifts through all the gears, but may be a little beat up, you should only have to pay from $500.00 to $800.00 depending on the condition and the reason the person is selling the bike. If you want to get a bike as a project, but would like to have it running when you get it so you can have some fun while working on the bike this is a good price point to look at. The best situation to find is a person who may have bought a CT90 , but now have lost interest for some reason and have no attachment and just want to get rid of the bike or you find people who ended up with the CT90 because a relative has passed away and also just want to get rid of the bike and don't have any idea what they go for or don't care. In these cases you can usually get a solid bike for around $700.00. Watch out for the person who is selling a CT90 where they say it was running just a year or two ago and that it just needs the carb cleaned a new spark plug, and a tune-up, but doesn't happen to run now. They may be telling the truth, but most likely they may have never seen the bike run and don't really know what it will take to get it back up and running.
A Very Clean Well Running CT90
If your not looking for a project and would just like a solid, clean, running CT90 that is close to original condition, expect to from $900.00 on up to $2400.00 for a perfect bike. A lot of times the price of a CT90 that has been fully restored is more a function of what someone has spent getting the bike into that condition and not what the bike is really worth. While seeing a stack of receipts for the parts and labor that may have gone in to a CT90 may give you a good feel for the condition of the bike, don't buy into that the stack of receipts now represents what the bike is worth. If you not too concerned about the cost of a CT90 then look around until you find one that starts first kick and is perfect in every way and pay the price, but you should be able to find a great CT90 in the $1100.00 to $1400.00 range that also starts first kick and is in great condition.

Recent Purchases I have Made
As I pick up new project bikes I will share what I paid, a picture, and a brief description so you can have an idea of what you can get for your money at the low end of the scale (which is the only bikes I buy) if you really stay on top of what becomes available on Craigslist.

In January of this year I was hunting around on Seattle Craigslist and I picked up the pair of 1969 CT90's in the picture below that were about 90% complete, but did not have motors for all of $20.00!

Just last month in April, I purchased the 1972 CT90 in the picture below for $80.00. Its been painted white and the motor is froze, but its about 95% complete so it will make for a great project.




Here is another purchase, its a 1969 CT90 that I picked up for $75.00. The kid I purchased it from said that it had been running a year ago and the had it set up to run directly off the magneto/alternator which I questioned, but the bike does have good compression and kicks over nicely. Another fun project.


Here is a purchase I made in August 2017 that was a 1970 CT90 that I picked up for $200.00. The bike is 100% complete and the engine is free with good compression. The seat and down tube plastic are in great shape and the down tube plastic still has the original decals. The bike was real dirty when I picked it up and the picture below is after I washed the bike. With fresh gas and a check of the points and timing, I think I'll have this bike running in a day or two... (Update 3/19/18) I thought I should add an update with respect to this CT90 that I had purchased as when I went to start the process to register the bike I found out it was stolen! You can read out my experience in dealing with a stolen bike at a post I made at this link.


Sometimes if you're lucky you can end up with a CT90 for free. I was helping a friend recently (March 2018) get a Honda CT90 he had purchased up and running and in return he gave me the 1976 CT90 in the picture below that had been setting on the side of his shed. The bike is very rough, but the engine turns over, so later this year when I get freed up I start working on this bike and I am confident that I'll have it up and running in no time at all.


I have a bad habit of looking at Craigslist on a regular basis and this week I was able to pick up the 1971 CT90 in the picture below for $75.00. It's missing the exhaust, but otherwise is complete. It didn't have a title when I picked it up, but the owner thinks he has it and if he finds it he will send it to me which would makes this deal all that much better.


As I continue to increase the number of bikes that I own, I do plan on selling a few as I get them up and running. The next topic I need to start looking into are insurance companies and getting insurance quotes, as owning and being able to ride a number of bikes I finding out comes at a cost I will be looking to minimize.

Last year on Christmas day (in 2018) I made the mistake of looking on Craigslist that afternoon and someone in Seattle was offering up three complete bikes and four incomplete bikes all for only $395.00 and the deal was good for Christmas day only. The person selling all the bikes had picked them up over the last several years with a couple of different projects in mind, but recently decided to downsize and get rid of a storage unit the bikes were being stored in and decided to let them all go for a song on Christmas day, which ended up making this one of the best Christmases ever for me. The following photos are of all the bikes and parts that I received from this purchase.



I was on the Honda Trail CT90 - CT110 Taptalk Forum recently (January 2020) on and someone posted that they had three CT90's and one CT110 part bikes they wanted to go to a good home and was only asking $100.00 for all four bikes. I sent the individual a message, and was able to get the bikes which also included a box of parts and they only cost $100.00 (no titles though...) and a tank of gas as the individual was 180 miles from my home. It was worth the drive and the picture below is of the bikes and parts I picked up.




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


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