Hello "PRO": I have a 2006 450 4WD Sportsman and it is backfiring badly when we de-accelerate. It starts very easy and I find it needs to be a bit higher on idle to keep it running. I checked the ECT settings during running and steering...no contact on those points. I then removed all the fuel and replaced it with FRESH-Today Bought high test which is 100% gas. I added a little fuel cleaner to the fuel. I replaced the spark plug. I used carb-cleaner and sprayed into the body while idile at 2200 RPM. Still backfires badly. We have just over 300 miles on this unit and do not know if any dealer service was conducted after the break-in period (if needed). I really need some help...THANKS!!

 

300 miles on a 9 year old machine..Sounds like it's done more sitting than anything else.You might be working around the problem. I'd take the carb apart and give it a good cleaning plus replace the needle and seat. Cheaper on this to just get a carb kit that includes it than to get an oem needle and seat.Plus I'd service the fluids,filters,etc from your owners manual.http://www.ebay.com/itm/POLARIS-2006-2007-450-Sportsman-Carburetor-Repair-Kit-Carb-Kit-/271928217870?hash=item3f502f510e&vxp=mtr

 

Thanks "PRO"...I just ordered the kit from your link...will advise on results...

 

use stabilizer once you get it running correctly if it's going to sit for any length of time so this might not happen again as well.