The countershaft bearing on my 02 yzf busted this weekend and blew through the side of my case. Has anyone had this problem or heard of any others who have? What was the cause? Are there any mods or things to check while cases are split? THANKS JimmyK

Was your chain REALLY tight? Just curious.

No the chain was not to tight but the nut that holds the countershaft sprocket on was really tight. The 1st time I changed the chain and sprocket I couldnt get the sprocket off so I went to the dealer and he used a impact gun to remove the old one and re-install the new one. When I changed the next time I did the same thing. I think that was the cause. Next time I will check torque specs. Expensive lesson, both cases have to be replaced at the same time. $500+... THANKS JimmyK

Tightening your counter shaft nut probably did not cause your bearing failure. I have been doing that procedure for the past ten years on Yamahas. Probably something like a stone got caught in your chain and took all of the slack out. A tight chain causes that kind of failure, or something letting go in the trans.