07 Yamaha 450 Rhino Backfire

[kooba]

My rhino 450 backfires very loudly when I drive for a period of time and take my foot off of the throttle quickly to slow down. It does it when its warm outside. I don't notice it when it cold/cool out. It this a timing problem or what do you all think?

[Dave S]

Backfiring is normally a sign of running lean. If you can get your sparkplug out, check to see what the tip looks like.

Many of the big 4 ship their machines to run lean from the factory to meet the California emissions regulations (green sticker). I'm willing to guess it's either a simple jetting change or an adjustment of the air//fuel mixture screw.

[Macgyver55]

A small exhaust leak can also cause backfiring.