Hi guys,

When reassembling the motor on a 73 CT3, the sprocket/drive shaft does not turn freely in neutral. I've taken it apart, removed the trans and reassembled 3 times now.  It spins freely until I put the cases together. Then the sprocket will move 1/2 turn total. 1/4 forward, 1/4 back. I'm stumped. Never had this issue prior.

Nothing is binding. Clutch shaft moves freely.
Tsmitty

Pull the right case off & leave it all in the left & see if you can eyeball the problem. Or could do the same in the right case except the selector drum is held to the left but might be able to simulate where it would sit if held left. Don't think the drum has a ridge to limit it in the right case although detent roller arm would do a reasonable job of keeping it approximate. OK back to the left case, sit it all in place & home in the bearings, CORRECT selectors in their grooves & turn the main shaft while engaging all gears by hand on the drum stopping at the drum high points which is max engagement of each gear & guess where neutral is between first & second. Easy with practice. If nothing locks up then slide the right case on & try again. Be sure the drum has its retainer holding it left above the sprocket there. Be aware that when engaging each gear you'll have to twiddle one shaft for dogs to engage and find their mate or will bump end on. With each gear engaged the mainshaft working from the right should revolve freely. Neutral the same. If attacking from the left with it all in the right case the same applies to the sprocket shaft & should revolve freely.

Just to add, you say sprocket shaft turns 1/4 turn each way which makes me thing the dogs are home & wanting to turn thenother shaft. I'm thinking if by chance you happen to be in top gear it'll take reasonable force to turn because you're trying to turn the main shaft at guessing 4 times the speed. So try a little force or find neutral or go through all gears trying to turn & remember for to get those naughty dogs back in one shaft will need a twiddle slightly. I'm working on the theory now that you might be A-ok & just in a high gear not neutral. In saying that, I know neutrals always talked about as critical for assembly--but it's not-- could be in any gear & makes no difference so long as all gears are in place & revolve as they should. Neutral is just good place to assemble so makes it easy to turn the shafts to be sure there free etc.

Thanks guys. I beleive I have gone through these processes. As long as the case is apart I can get it to turn freely. Once the case is back together, it creates the problem. Then, when I resplit the cases, I have to remove the trans to free it back up. Put it back together and it's fine until the cases are back together.

I know I'm missing something small and stupid. That's usually the case.

The "U" shaped keeper behing the sprocket is missing the shim. Ordered the part and will arrive tomorrow. Although I don't believe that will fix my issue.
Tsmitty

I think you mean the shift drum shim is missing?  That definitely could cause the issue.

Hi Mark,

I believe so. On Prtszilla it's called the shift cam?

Only 1 shim on it and that's what's missing.

Half the fun of these old bikes is figuring out what modifications and parts left off by previous owners!
Ts