i just bought it yesterday, it's a 2002 yz 250f. i brought it home from the dealer and started it and it was backfiring, popping, and had flames shooting out of it, is this normal? i called the dealer this morning because the were closed by the time i got the bike home last night, they said somebody probably jetted it. im really upset about this because the reason i bought a bike from a dealer is because i wanted a bike that was looked over and made sure it was it good operating service before was sold, i just wanted that reasurance. even when the bike has been running for 5 minutes it does this and it also doesnt idle. i talked to someone i work with and his friend has a 250f and he was with him yesterday and he said that his doesnt do the backfiring, popping, etc... i just want to know if this normal. there is also no warranty with this bike and im kind of scared.