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Discussion Starter · #1 · (Edited)
Edit: Solved I think, got frustrated and took a hammer to it lightly, and after a couple smacks the bearing seems to seat and spin normally. Not quite free bearing spinning but reasonable now

Hey guys, I split the cases yesterday on my cb160 engine to inspect and clean.

The only thing mechanically wrong was a slightly bent dowel in the countershaft bushing spot.

I replaced the bent dowel (correct length) with one out of my spare engine, reassembled and noticed that the transmission shafts were very hard to rotate. I then disassembled, put the bent dowel back in and found that the transmission rotated easier (but still not freely) than with the new one.

So I put it all back together one more time, and its better but not what I'd think of as free rotation. It does shift nicely up and down through all the gears.
I've attached a video below, rotating the mainshaft in neutral.

 

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Discussion Starter · #2 · (Edited)
Further investigation:

Tried the countershaft in two different crankcases, 2 different bushings and 2 different dowels and in all combinations when it fully seats into the little half ring while also having the bushing fully seated on the dowel, it gets very hard to rotate.

I think the tightening of the cases with the bent dowel by the PO must have bent something in the countershaft or maybe pushed the bearing slightly off center. The only other thing I can think of is that the set ring/circlip is bent out of shape enough to change the length of the assembly and cause things to no longer fit

If there's something simple I'm missing let me know, otherwise I guess I need another transmission...
 

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It should turn free. I like mine to spin easy with the touch of a finger. Split the case and put the shaft in the case half and check the end play. Ive never worked on a 160 motor but would think .15 would be about right. Also strip the shaft and use a dial indicator to see if the shaft is true . Take it to a machine shop or high school shop if you dont have an indicator. If the shaft is true and you dont have any end play check your bearings and if ok then start looking at the gears to see whats out of shape. Also check the shift forks to see if they are bent maybe putting pressure on the gears. Get a full service manual and see if the shaft is assembled right.

May be none of the above but its a start. Some thing is bent or out of round . Good luck.

Bill
 

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Discussion Starter · #4 ·

This is after tapping it into place (first shows rotating the countershaft then the mainshaft). Still not quite like spinning it outside the cases but the resistance is gone now. I want to say I just didn't have the bearing seated in the retainer but it also seems like with a Honda motorcycle if you have to use a hammer there's probably something wrong

Thank you for the checklist, I might just invest in a dial indicator and do it properly. I've got the service manual and all the specs are in there.
 

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I think the shaft looks pretty normal to me. Even with the transmission in neutral there are gears on the shaft that are turning on what effectively are bushings. These will make the shaft feel a little 'draggy'.
 

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Discussion Starter · #6 ·
I'm thinking it's okay now too. It definitely wasn't before but after tapping it into place it feels like what I'd expect.
 
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