bought a new 03' rubi. its runs great, but when i'am goin down hill around 25-30 mph it backfires. the engine breaking slows it down,but i'am wondering if i should be goin slower or if this is normal, or do i need a vavle adjustment, or do i have other problems with the machine. thanks

 

Put a few miles on it. The backfire is an indication of it being too rich.

 

My Son's new Recon backfired for a bit then it cleared up after it had more miles on it, his just needed to be broken in if yours doesn't clear up take it back to your Dealer and have them look at it just to be on the safe side.