CT90 Shifting Sticks

H

Honda Hornet

Member
The shifting on my 1978 CT90 K9 is not smooth and occasionally it gets stuck in 3d or 2d when downshifting, especially when not rolling. So far (2000 miles ridden since I got the bike running in August), I am always able to get things back to normal by gently turning the throttle until there is a klunk sound and I can shift down and go on. It never seems to happen if I down shift gradually as the bike slows (i.e., always works while the drive is engaged).

I am planning to do an oil change soon, and I plan to take off the clutch cover off and clean the oil spinner and the filter, and I will take photos of the shifting parts. If anyone has an idea of the likely problem or part I should focus on in my examination (or replace, of course), please let me know.
 
OLD CT

OLD CT

Well-Known Member
If the clutch is adjusted properly and not beat, then the other thing it could be worn shift forks. As always, only use 4 stroke wet clutch motorcycle oil.
 
H

Honda Hornet

Member
Thanks Old CT.

Confirming clutch adjustment done and clutch performs as expected both at startup and providing power at high RPM. Since purchase I have used Valvoline 4-stroke motorcycle oil (not synthetic) that label says it is for wet clutch.

I will look at my manual for shift forks. Would you recommend I buy replacement prior to opening the cover, as very likely the problem (and less time without my transport)?
 
B

b52bombardier1

Well-Known Member
My guess is a loose shift drum stopper star plate. Or a bent roller arm that rides over the hills and valleys of the star plate. All of this is on the rider's right side of the engine under the drive gear.

Rick
 
OLD CT

OLD CT

Well-Known Member
Sure would be worth poking around in the clutch cover like Rick suggests before digging in all the way.
 
H

Honda Hornet

Member
I don't think I will split the case if that is required, as the problem is intermittent and manageable for now. I will definitely examine the star plate and its roller arm, if I can get to that reasonably.

Thanks for all the suggestions.
 
J

joel1234567

Active Member
This sounds like normal ct90 shift behavior to me, if I'm understanding correctly. They really don't like to be shifted more than one gear while stationary. If so you often need to rock the bike a bit. I think that's normal.
 
H

Honda Hornet

Member
Thanks, Joel. I had a couple C70s in the 1980s, and I think my CT90 shifts down worse than either of them, but I was already thinking that it is tolerable. I never have problems shifting while I am moving, so I appreciate your comment.
 
G

GaryG

New Member
Honda Hornet said:
The shifting on my 1978 CT90 K9 is not smooth and occasionally it gets stuck in 3d or 2d when downshifting, especially when not rolling. So far (2000 miles ridden since I got the bike running in August), I am always able to get things back to normal by gently turning the throttle until there is a klunk sound and I can shift down and go on. It never seems to happen if I down shift gradually as the bike slows (i.e., always works while the drive is engaged).

I am planning to do an oil change soon, and I plan to take off the clutch cover off and clean the oil spinner and the filter, and I will take photos of the shifting parts. If anyone has an idea of the likely problem or part I should focus on in my examination (or replace, of course), please let me know.
Click to expand...
 
G

GaryG

New Member
I have the same sticky shifting problem with my 1968 KO CT90 with dual range transmission. I strongly suspect that my "shift drum stopper" may be bent or otherwise damaged. It is also possible that the clutch may be out of adjustment or clutch plates may need replacement. It is also possible that the shifter forks may be worn. It is also possible the transmission gear "dogs" may be worn. At age 85, I am reluctant to remove the right side cover and clutch basket to get access to the shift drum stopper, etc.

Be aware that the semi-automatic clutch is a sophisticated device that has a centrifugal engagement feature that disengages at idle rpm and engages at higher rpm to help with smooth acceleration and shifting. I have read that the bike must be rolling to enable shifting.
 
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