This is a clarified version of my earlier post. 03 YZ450F I bought about a month ago. Runs awesome until it gets a good hot soak (couple miles or 5-10 minutes depending on how hard I ride it), then, SUDDENLY, it has no throttle resonse, and putts along just barely running for about 30 seconds, dies, and will not restart until it cools off. Then it will start great and run great for about the same amount of time until (I assume) is gets hot soaked. So far I have: cleaned the carb rejetted it down two sizes (pilot and main) - and plug now looks pretty good checked the airbox and filter for obstruction replaced the plug (new) replaced the coil (used) replaced the stator (used) replaced the wiring harness (used) Previous owner replaced: CDI box with a new Procom unit (looks new and I was given the box). full C4M exhaust and header Now that I have some spares, I rode it at Silver Lake last weekend, and it does, in fact, not have spark when it dies hot. Nice bright blue spark cold (way better than my 426). When it dies it will come and go (a bit) if I keep the throttle cranked open while it is sputtering (putt - putt - putt - putt - riiiiiiiip - putt - putt - riiip - putt - putt - putt - putt - putt - die). What 15-20 minutes. Good as new again. What am I missing here?