GoesTo11

Member
Aug 21, 2000
17
0
My neighbor has a 2001 YZ125 with about half a season on it; bottom end never touched; original clutches. The case cracked on the left side immediately in front of the drive sprocket. It appears that the shaft that goes through to the clutch hub is putting pressure on the case. The case has a circular break (approximately 1-2 inches in diameter) that has gone almost full circle and has pushed the broken part out about 1/8 of an inch. (The area breaking out appears to be cast for the shaft/bearing.) The clutch hub has no play at all, but the outer basket has quite a bit of play. Any ideas on what could cause this?

Thanks
 

KawieKX125

~SPONSOR~
Oct 9, 2000
948
0
Did the chain derail and crack the case?
If not and if it is purely a casting error, then the yamaha dealer should replace the part for you since it is such a new bike.
 

GoesTo11

Member
Aug 21, 2000
17
0
Originally, my neighbor thought that a loose chain had caused the problem by contacting the case. However, closer inspection shows that the case has never been touched by the chain (or anything else) from the outside. It apparently is being pushed out by some type of pressure from the inside.
 

msport

Member
Sep 4, 2001
29
0
RE: Crankcase cover

The left crankcase cover is for the ignition. It could be a loose rotor nut. Did you take the cover off to inspect it? I replaced the plastic cover on my '01 YZ125 with a magnesium one, cuz the plastic is chintzy. If you're interested in a replacement plastic cover let me know. I still have my original one, in good condition.
 

Ol'89r

LIFETIME SPONSOR
Jan 27, 2000
6,961
45
Goes To 11.

Chain too tight????

If the rear chain was not properly adjusted, it could cause this to happen. When you adjust your chain, you have to compress the suspension inorder to check for proper slack. If you adjust the chain without compressing the suspension, the chain will be too tight. When the suspension compresses, the chain will get tighter. If it is too tight to begin with, it can break out the area that holds the countershaft bearing.. I've seen it happen before.

Refer to the manual for proper adjusting procedure.

Just my $ .02
 
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