Arctic Cat 440 Sno Pro

I just bought a CA 2002 440 Sno Pro and have a problem with it! When I travel, it seems half the top speed it should go (40 mph) rather than the usual 80 mph! When I get up to 20 mph, the slowdown in 6000 and I lost power! What is the problem! Should I run the 1 piston only???

Any idea??
Thank you
Ben

I assume that your snowmobile is running normally at low speed, which means that the engine is OK mechanically. It could be that your ignition / spark plug is quiting at higher speeds, but more than likely you have a carb on a dirty side. Want to stop running the sled until you make sure that the carbs are clean, because if one side is clogged it will run lean and seize the piston. Carb cleaning is not rocket science, but it must be done well, check with someone who has experience in carbohydrates.