Hello all. First post on here. Came across the website while searching on a problem with my 98 KX250. I have a 98 KX250 that has a vibration and rattle that started about 7 rides ago. The vibration increases as the motor revs and seems pretty slow at idle. I bought the bike last november and it didn't have it when I first bought it.The rattle is from the power valve, which I inspected after I took the Head and Cylinder off. The valve as a whole looks fine, as does the cylinder and piston. The engine vibration is causing the top "flap" of the power valve to rattle when opening. The rattle starts when the valve starts to work. My question is does anyone have an idea on the vibration. I took the flywheel side of the motor off to look for play in the crank bearings. No play at all, everything looks, sounds and moves perfect. My clutch seems to have alot of "chatter" in neutral. Could a worn clutch cause vibration in the motor. It ingages fine and does not fade or slip. I just don't want to have to take more apart then I have to to get it solved. Any direction would be great. Thanks