My 2003 stock 100 XR100 road racer has developed a vibration only at idle. Really weird and I'm sure it has something to do with me jamming down two gears and revving the pants off of it coming out of the back straight at top speed. I find it really odd though that I don't feel it anywhere other than idle. I would expect it to get worse as the RPMs increase. It starts normal. It idles fine (other than the vibration), it runs like normal. Any suggestions on where to look first? The season is almost over and I'm going to finish on this motor unless someone is 95% certain it's about to throw a rod or something that will completely trash the motor is going to happen in the next, say five hours of running.