I have a 1999 yamaha warrior. I have sheared two keyways between the flywheel and the crankshaft. I have had nothing but problems with the starting system since i bought this machine. This is the only problem I have left. Any idea why this would be happening?

 

if something is out of timing a little bit or a bolt holding a gear is not torqued within spec i think this can happen i always create a little "nick" into the key that way the key actually wedges into the keyway using a hammer and tapin it gently, i never just take a key and drop it into the keyway to where its loose, when i install keys the nick i create makes it to where the key wont just move around very easily when its in place, ive also heard of people using loctite to hold a key in.

 

Would forwarding the timing one tooth a the cam sprocket cause this?

 

yea probably, it shouldnt be out of timing like that, the timing marker on the cam sprocket should align with the mark on the head while the bottom mark on the stator lines up when u pull the rubber window, the cam on warriors shouldnt be advanced or retarded at all, on some twin cam bikes u can do that for a power change but not a single cam warrior.