2006 sportsmen 700 efi backfiring after a wot jaunt I recently cleaned k&n filter and refoamed ........at first I thought it was just the oil from the foam getting sucked in but that was 2 rides ago.....probably 60 miles on after I cleaned filter. I didn't put the polaris pre filter on over k&n filter......got about 1000 miles on machine with K&n filter with no previous backfiring issues.....

maybe bad gas?
water in fuel.....I'll have to try some dry gas...maybe?

 

Many postings on backfiring....Could be a pinched vent tube, bad gas, maybe air box not installed just right....Could be something got in fuel line?? Fuel filter??

 

Check the tube that is about 5/8" in diameter under the airbox just in front, see if you have a kink or cut hose. I had a cut in mine, back fired all the time, replaced hose and no more

 

My 09 850 XP was backfiring. The dealer adjusted the throttle cable (throttle position sensor) and it seems to have cured it.

 

Been there done that! those new TPS are very sensative.

 

how about the valves? when was the last time they were adjusted?

 

thanks

I'll have to go home and check vent line...sounds like thats were everyody is heading me