drive sprocket please help thank u

sirenson

New Member
Mar 24, 2013
7
0
1
miami
hi
i recently changed my drive sprocket to a 415 but the id was different so i put the 410 back on (tight and proper) but the drive shaft now has a lot of play in and out of the engine. did i loose a shim or something? something between the engine bearing and the sprocket? does anybody sell whatever i lost? is each shim custom made because of subtle sprocket id differences causing a change in the gap between sprocket and bearing? perhaps this has nothing to do with a shim? perhaps some mystery problem behind the clutch?
thank u
 

LR Jerry

Well-Known Member
Dec 19, 2011
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Rockwood, TN
Are you wondering if you lost a key for one of the keyways? The good news is yes you can get replacement keys. The thing is though you have to precisely know exactly what size and shape the key needs to be.
 

sirenson

New Member
Mar 24, 2013
7
0
1
miami
i didnt lose any keys luckily. but for forum fyi here is some key info from fred chelminski @ cr machine shop ( he builds great engines)

There are about 3 versions of sprocket;
One uses a non tapered bore,
and the other two are tapered bores; one with a 2.5mm wide woodruff key, and the other with a 3.0mm wide woodruff key.

my problem is not keys. it is play between the fully seated sprocket and the driveshaft bearing (the shaft moves 1/8" in and out of the engine). here is a copypaste of an email w fred

regarding clutch preload spring. (collar preload). i figured as long as im in there i might as well check it because maybe if it came loose, it caused the 1/8" play by pushing the bearing out. a bikeberry video says 10 rotations on the clutch collar. they must be wrong because, starting from totally unscrewed, after about 4 rotations the spring is nearly totally compressed. how many rotations do u suggest?
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,807
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up north now
I remember my sprockets having some play (never measured it).
I would put it back together, and turn the "preload" until the clutch doesn't slip.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,807
204
63
up north now
To clarify- I don't have one here right now....waiting on my kits. My dad sold the one I gave him for fathers day, so I can't check that bike.