I just bought the bike back from a guy that I sold it to in 1989. He bored it out to ? cc. All I know is that he used a wisco piston. Overall, it runs better than it ever did when I owned it. It pulls like a tractor. But.. 1. I'm getting a loud ping when she's opened up full throttle in 4th + gear. 2. And the thing feels like it's in need of a front end allignment? Clues: I ride on mostly New England power lines & trails I'm running 10 40 Spectro oil I ride fast I use high octaine gas It has a K&N air filter It has a Supertrapp exaust(P.S. I'm need of a header) Please tell me what I'm doing wrong and point me in the right direction. Thanks for your help Nubie with old school 85 XR 600+?