I have a 1998 Yamaha Grizzly 600yfm, AMD recently went to running really rich. I noticed that the suction at the carburetor was not there so I check timing it appears to be about 3 to 4 teeth off. I have approx 83psi of compression, and has had some piston slap in it for a while. My question to everyone on here is with that all wrong, am thinking of doing the wiseco 635 big bore sleeve kit. Is that a good thing to do on an aircooled motor, and if I do that and have heads worked over should I put a better cam in, and what is suggested if I do? Any info would be greatly appreciated. Thanks