i have a 2000 yz426 with the 450 hot cams installed. i was riding it around last saturday and it was running like a champ, no bogging and started right up on the first kick. so i was on the way back to the truck to put more gas in it, it had about half a gallon left in the tank, when it suddenly started to sputter and then died and locked up. so i put it gear and rocked it back and forth, loosened it up and now the thing wont start. i have checked and changed these items: replaced spark plug and there is a white ish blue spark valve clearence is good timing is dead on cleaned out the carb, it was pretty dirty and verified it has fuel flow air filter is clean the fuel vent cap works and there is good fuel flow coming from the tank to the carb i have been trying to figure out what the problem is, i can kick the shit out of it, and it may start once or twice that night, but only run for a split second then it dies.any help would be appreciated, i don't feel like paying 75 bux an hour for some shop to diagnose it.