OK, I recently bought an '00 XR650R with approx 1000mi on it from a riding buddy who was forced to sell. It was uncorked but otherwise stock condition. Since then it has a full FMF system, Uni Airfilter, 1.6 rad cap, Critter fix right side peg, IMS folding levers, etc. I also opened up the airbox and now it flat out rips. Problem is after riding it for 15 or twenty minutes, (any speed) it idles high for approx 20 seconds then returns to normal idle. Blipping the throttle or engaging a gear slightly doesn't help. Carburator is stock minus the baffle. The main jet is a 175 (recommended by FMF) the pilot is stock, maybe an "S" version??? Valves are within tolerances, no airleaks that I can find and it starts on first kick. Throttle cables are good, no kinks, and are brand new. I did a search and this seems like a commom problem, but couldn't find one common fix. Most people suggested rejetting, maybe thats what I need to do. I should note the previous owner had the same problems before I added all the mods. Any ideas would be greatly appreciated.