Hello Dave,
I will forecast that its a problem with the shift drum stopper or the star plate on the end of the shift drum. You will need a right side engine case gasket plus an outer clutch cover gasket. For tools, a Japanese Industrial Standard #3 screwdriver is needed to remove the right side engine case screws. Trust me please . . . they only APPEAR to be a Phillips head. An impact driver with a JIS bit might also be required here. The outer clutch screws will need a JIS #1 bit for removal. Expect some oil sludge buildup in this area and it definitely needs to be removed. And with the case cover removed, lift the gasket up from the lower right side front of the center case to find the oil screen. Its a black rectangle that needs to be grabbed with needle nose pliers and removed for cleaning and there's no telling how much grunge might be there since these rarely got cleaned. Bits and pieces of Jimmy Hoffa might be there . . . . who knows?
A clutch nut socket will be needed to remove the big nut on the clutch after tapping down a keeper. Then you will need a snap ring tool to remove the main drive gear. Once its gone, you will finally be able to fully view the shift drum area. A strap wrench to hold the clutch while removing the nut is also almost a necessity. You will also likely need a friend to help hold it all while the nut gets removed unless you have two extra arms on your body. I prefer the Honda special tool to hold the clutch rather than a strap wrench because engine oil often makes the strap wrench too slippery.
The roller on the end of the shift drum stopper could either be missing (metal fatigue broken) or the roller and arm could be flexed up and riding on the top of the star plate. It needs to be rolling around the edge of the star plate to keep the shift drum properly indexed.
If the star plate screw is loose, make sure the hole is clean and all of the pins are in the end of the shift drum. Then use red Loctite to firmly plant that screw into the shift drum.
I have also heard of bent shifter shaft problems and the "claw" on the shifter shaft that ratchets the drum being worn down. Then we can also mention bad shift forks inside the center cases. But my money is on something easier to fix for now.
Jack at
DrATV OPERATES HERE will have the gaskets and any other parts you might need. You can download a free shop manual for the CT90 below and the procedures for the shift drum area are the same in both bikes. Pick the manual for the 1977-82 bikes covering the CT90 and the 110 as it is the best of the bunch.
| Shop Manuals
Rick
