Hey everyone, My bro has a 03 660 (686) raptor and here while back it just quit running wouldnt fire, well got that fixed it fires now. it was the cdi came off another running quad but it will not start it just backfires LOUDLY. any idea (its in time) ,we checked that he thinks maybe a bent valve havnt checked compression yet but sounds like it still has good comp.we need help please let me know thanks

 

First check the carb boots, they'll cause this problem if they're not tight on the carbs and head intake.

Next is your vavle lash, if it gets too tight it'll be a bear to start.

Try push or pull starting the bike. If it will do that then check the valve lash.

 

Head gasket or exhaust leak?

 

ok guys thanks, ill let him know maybe he can work on it today