HELLO GUYS I HAD A PISTON MELT ON MY 02 VIPER. IT WAS THE # 3 CYLINDER RIGHT SIDE IF YOUR ON THE SLED. THE FRONT OF THE PISTON MELTED AND A SMALL PIECE OF THE TOP BROKE. THIS OCCOURED TRAIL RIDING AT 10-15 DEGREES F. SNOW ON TRAILS WAS OK NOT MARGINAL BY ANY MEANS. I GOT NO OVERHEATING WARNING FROM THE SLED UNTILL IT WAS TOO LATE AND I NOTICED A BOG IN THE ENGINE AND PULLED OVER. MY CAMRA IS SCREWED UP SO I DONT HAVE PICS.(SORRY) I HAVE HAD MANY 2 STROKES BEFORE NONE WITH POWER VALVES. THE PISTON MELTED ON THE POWERVALVE SIDE OR FRONT AND IM WONDERING IF THERE CAN BE ANY AIR LEAK ISSUES THAT I CAN CHECK FOR. THE PLUGS FROM ALL CYLINDERS APPEARD TO BE RICH IM NOT THINKING A LEAN CONDITION WAS THE CAUSE. I HAVE ALL NEW PARTS TO REBUILD SO I WANT TO BE SURE THIS WONT HAPPEN AGAIN. MY JETTING QUESTION WOULD BE WHAT SIZE TO RUNN FOR NH / CANADA RIDING TEMPS NORMALLY 0-32 F. ALSO IF ANY ONE CAN TELL ME NEEDLE CLIP SETTINGS AND HOW MUCH THEY CAN EFFECT THE JET. LAST BUT NOT LEAST IM ALSO WONDERING ON THE HEATED CARB SITUATION TO RUN THEM OR NOT? THE GUY I BOUGHT THE SLED FROM NEVER DID JUST CURIOUS. THANKS IN ADVANCE FOR YOU THOUGHTS AND HELP I JUST PUT A 1000 INTO THE REBUILD DONT WANT TO EVER HAVE TO DO IT AGAIN!!!!!!!!!!! 
On a day that cold you should run them just for the fact it makes you one size richer. look more towards water in the gas than anything. What is your jetting at now. Maxdlx
I Havent Pulled The Carbs So I Dont Know The Jetting Yet I Will Post When I Know. THANKS
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I Will Try To Post Pics Of The Piston If I Can Get A Camera!