Gerbil is a dick dont listen to him, he gets beat all the time in hillcross.
That being said I would check out your carb and make sure it is completely in order. Last winter Rubi (another douche on here) had the tip of one screw broke off in his carb and he spent the whole season pulling his motor and checking his crank and rebuilding his whole sled all the while it was just a simple screw tip. He was having issues with backfiring which started his whole fruitless endeavor.
well i just bought this sled and its been sitting on a trailer for about a year now... i just started it up once i got home and noticed it backfires like crazy...so i was thinking hopefully its just bad gas or the carbs need to be cleaned..hopefully its nothing to serious?
Once you get fresh gas and clean the carbs you can run it on a stand to see if it gets better. Get your problems figured out before there's snow in the forecast. Does your sled run like mine did in the video?
Get your carbs off and clean them thoroughly. Pay special attention to the pilot jets and the fuel screw circuit. Remove the fuel screws and put the little red straw attachment for the carb cleaner right into that hole. Make sure the carb cleaner is coming out the little hole in the bottom of the carb bore. Reverse that process and make sure the carb cleaner is coming out the fuel screw passage.
Siphon as much of the old gas out as you can. I put my old sled gas in my car. Some people throw the gas away, but I'm a tightass and drive a '98 Ford Contour with 200K miles. My car loves old sled gas even if it's premixed. Put two or three gallons of fresh gas in and siphon that out. Then top the sled off with good gas. Now you've eliminated bad fuel as a problem.
Once you've got your clean carbs reinstalled, get your sled up on a nice secure stand. Warm it up and start putting it through its paces on the stand. After some full RPM pulls, it should start running better. If it doesn't I'd clean the carbs again twice as carefully. Then you can move on to other troubleshooting.