Clutch Rebuild

GoldenMotor.com

gebhardm

New Member
Jul 5, 2010
33
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0
Illinois
Well my relatively new 80cc motor has been running great. Yesterday I was taking my evening ride when suddenly the engine rpms went high and I lost power (essentially zero torque to chain sprocket). I set about trying to remedy the problem by
1. checking the cable
2. adjusted both the star nut and the clutch main spring.

neither of these things helped so I began to look at it more closely. Thanks to the helpful post at this website I completely dismantled the clutch and in so doing I found the problem, The woodruff key on the sprocket side was sheared off and the main threaded bar was also damaged. I've ordered the parts and I think I can put is back together. I have one question though. Behind the chain sprocket were 6 or 7 (I didn't count them) very thin washers. IS THIS NORMAL? I've not seen them referred to on other posts related to clutch or drive train problems.
 

biken stins

New Member
Jul 11, 2008
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Just my guess the washers may of been for alignment never have heard of it. Might check.
The question I would be asking is WHY the woodruff was sheared. Something locked up ?
Good Question and good luck to you.
 

gebhardm

New Member
Jul 5, 2010
33
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0
Illinois
Stins- Thanks for the input but I don't think anything locked up because the motor was still running fine and the large and small gears still moved nicely. I plan to go to some of the local machine shops after work on Monday and see if they have anything similar they could sell me. These washers are really thin, almost like printer paper. I do have another question as well.
There seems to be some inconsistency in the threads as to how one adjusts the clutch main spring. Both methods direct one to remove the bolt on the top of the clutch housing (the one the cable passes through) and place punch or screwdriver in the slotted nut located on the clutch shaft. SO here is where the inconsistency starts. Some say to turn the nut on the sprocket side to the right. Others say to turn the sprocket left (counter-clockwise or the way the engine turns the sprocket). Do these two suggestions amount to the same thing?
 

biken stins

New Member
Jul 11, 2008
156
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Never worked with that spring. Both may work. My rule of thumb is listen to Norm. His section has been right on for repairs i've done.
 

corgi1

New Member
Aug 13, 2009
2,272
3
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KCMO
The spring refered too is to increase pressure if the rod w/the flower nut goes on were to have play (loose,rattle)or the spring be tightened way too tight ,and the cutch hard to operate,Hopefully my memory is correct on this,,,,I would look in stiky notes for Norm's (Poss.PM him) threads on the sproket /clutch thing,I dont remember shims ,I thought the thing was tapered fit and shims would defeat that
 

gebhardm

New Member
Jul 5, 2010
33
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Illinois
When I took the clutch apart the main clutch shaft was ruined because when the woodruff key sheared it tore up the end of the shaft. Basically the chain sprocket was spinning around on the ruined shaft. I ordered basically all the parts from Piston Bikes and this included the clutch shaft, main clutch spring, the part that slides inside the main clutch shaft (sorry I don't know what it is called, but it is the part to which the large gear on the other side of the engine is attached), the pin that holds that unnamed part in place on the main clutch shaft, and the slotted nut that threads on the large clutch shaft and is used for adjusting the main spring tension. I also order two woodruff keys since one is needed on both sides of the engine. The whole thing came already assembled and greased so I didn't have to put the parts together although I am glad I took the old one completely apart because it helped me understand how the whole thing works. It wasn't that big of a deal removing the old clutch and replacing the parts You just have to kind of think it through. Probably the hardest part for me was putting that small woodruff key into the slot and lightly tapping it into place. It would move a little (that's all) so I had to try a few times. I replaced the large gear and the sprocket, reattached the chrome clutch plate, and the bike has been running fine since then. One more thing. Look at the parts carefully. My chain sprocket was also slightly gouged when the shaft and woodruff key failed. I didn't see that at first so then had to order a sprocket as well (got it from Kings Motorbikes I think). The old sprocket might have been OK but I figured better safe than sorry. So I'm not sure this was helpful but hopefully you will be back on the road soon. By the way I did not reinstall the thin washers and in my opinion they are the reason the whole thing failed in the first place.
 

corgi1

New Member
Aug 13, 2009
2,272
3
0
KCMO
The sproket may have been damaged or had a burr when they originally put it together in china ,that may explain the thin thrust washers used to compensate for possible varied machining,maybe two or so stuck togeather while on the assembly line,, that the sproket may not have been seated properly on the shaft and was the cause of spinning and key failure