So I just picked up a 2006 YZ250 rebuilt by JGR with an new case and refinished and re coated cylinder (no motor mods but 2013 cases were used) which currently has 3.6 hours on it with a few after market motor parts like vforce reed system, and a full pro circuit exhaust. When I first rode the bike the vibration didn't really seem that bad at all. I took it to the track saturday and rode it and it seemed that the vibration got worse, almost so bad to the point where it gets hard to hold on when i give it gas since it vibrates soo much almost to the point of a shaking. I checked all the motor mounts and practically every bolt on the bike and made sure they were all tight, a few were barely loose whatsoever but it still vibrates horribly. Just for an example if its sitting there idling and I rev it it almost forces my hand of it vibrates so much, when it vibrates as well it sounds like ll kinds of metal is shaking against each other and as if the a few exhaust and motor mount bolts are really loose but they're fine. I plan on ordering some fasst flexx bars but I don't think that will fix the problem. The only things I could find by searching was some people saying that crank bearings can be going bad or a cheap quality crank was put in and/or its out of balance. As well as a flywheel weight being out of balance, installed incorrectly or going bad. I haven't checked the flywheel weight yet and I really don't wan to have the motor torn down again If i don't have to. Just spent over $2000 fixing a 250f that i traded this bike for. Quite violent vibrations? no loose bolts? Any suggestions? Also did an oil change after i got the bike before i rode, the oil still looked brand new but found this stuck to the oil screw magnet. No physical damage, scarring, its not broken. It's like a roller bearing almost but how it got there i don't know. Figured it accidentally ended up there after reinstallation since i couldn't find where it could come from without already have of locked down the motor or got chewed up at all.