my 2002 yzf 250 will shut down after about 35-40 min of riding. have ruled out carb and valves as possible problem. most likley an ignition problem have trouble shot ignition system with service manual everything checks out. something in the ignition system is probably heating up then failing. thought of running bike until failure then checking ignition system while componets are hot, but manual only gives specs for componets at 68 degrees F. hate to start shot-gunning parts. any advice would be greatly appreciated. p.s. bike starts first kick when cold runs great until time period specified above.