Hello all... glad to find a forum only for mini bikes. I got a coleman ct200u-ex...ive done some mods..echaust, intake filter and carb modify. And redone the throttle assembly and governor delete. Ive changed to the #40 clutch and sprokets, on the jackshaft also. But now im getting a really bad vibration in the bike at half throttle and beyond. I went to the #40 chain setup because i thought it was a heaver duty chain. Did i go wrong? There is no way to adjust the slack in the drive chain from the clutch to the jackshaft..and thays where i thjnk im getting the vibrations. Only way to tighten chain is to use a half link. The tension roller is baisically against the jackshaft sprocket. What am i missing? Where do I look next? Any help on this is greatly appreciated. Is there a way to do away with the jackshaft altogether? Has any one had this issue and corrected it?