Pretty much everything flexes on the 900 frames (Z1 and KZ). The older Z1 frames had smaller diameter frame tubes and less bracing at the head, but it's worth checking both frames for cracks at the head from wheelies/crashes. The KZ frame actually flexes a lot less than the older Z1. In addition to the frame, the forks flex, the swing arm, and, if you have spoke rims, your wheels will be flexing as well. BUT, the flexing inherent in all of these components should not cause any kind of sudden "hop" in corners (unless you're totally off the throttle in which case pretty much anything could happen). So, as has been mentioned, you can brace the frame, and you can brace or replace the swingarm, and buy a brace for the forks. Of course, you should make sure that you don't have any other issues, and it sounds like something is not right - all the flex and proper technique should result in predicatble "wallowing" - no "hops", so check your drive chain, fork action, rear shocks, front and rear wheel alignments, wheel rim runouts (and maybe even balance), and by the way, if you're grinding some kind of crash bar/case savers in the corner then this will produce some "hops", that is, until you're catapulted off the road - take the bars off and get a low profile timing cover.
Post edited by: jenshhj, at: 2005/10/18 11:25