2002 Sportman 500 HO
 

Lately my Polaris is noisier at the exhaust and backfires in the carb when I give it gas, no power. Someone told me it is the cam. My ATV only has 3,200 mi. or 720 hours. If it is the case, how big a job is it to replace cam and exhaust valve.

If you have an exhaust leak fix it first. That may solve the problem. You 2002 Ho cam was past the ones that had faulty heat treatment and wore down,but not a bad idea to check valve clearance(.006 clearance on intake and exhaust valves) and look at the exhaust lobe for any scoring or wear. Again if the gasket at the head pipe or the donut gasket where the head pipe joins the main pipe is leaking,fix this first.If you don't have a manual,this cheap one can help on setting valves or any other problem or repair that's needed.2002 Polaris Sportsman 500 Service Manual PDF Download Easy to get to tdc to check the valve clearance. When cam sprocket alignment pin is center of the head you should be able to see the tdc mark on the flywheel through the recoil timing check hole.This is in the manual also.

Thank you for your prompt reply. I will check the exhaust first.