2001 polaris 500 sportsman HO
 

Hello , hoping someone can help shorten up my search for a fix..starts good runs good ..throttle up and she pops and back fires..same when riding, no power. Limited giddy up. I have snorkeled it and ran it for a season.just took apart carb and cleaned..someone suggested jetting to accommodate to much air now? ? Maybe top end?..why would it run so good for a summer then just all of a sudden do this..?? Don't wanna take apart top end until i have explored all the easier options. Thanx in advace Lawrence

Welcome to the forums..Hopefully shouldn't be a cam problem as this was the first year of the improved HO cam.I'd still check valve clearance and the cam exhaust lobe. One other thing that can cause limiting(not necessarily back firing) is if the plastic limiting nut on the drive clutch backs off it can limit clutch travel and power.Item #8. If you've been in a lot of water also might be a good idea to pull the recoil and clean the pickup coil and flywheel from any accumulated dirt. If that doesn't help then you could be having an electrical break down. A test light can tell if it's electrical or still a fuel or mechanical problem. If the test light stays constant when it limits and pops back then probably not electrical. If the light flashes in time with the miss,then possible electrical problem. There are good checks and tests in the service manual also that can also help narrow down the problem.https://www.tradebit.com/filedetail....ce-manual-2001

Thanks for the tips I will keep you informed ..I have been reading alot and trying to get more educated on the matter.I performed a compression test 100 lbs x 3 ...then with choke pulled 115psi x 3 , and with choke on and full throttle 175 psi x 3..so I'm thinking not valve issue? ??

Compression not normally that high. 55-90 psi on average,some a little higher,but because of the compression release device compression should not go much higher than that. You might check also if the detent spring breaks or slips it can cause the same thing as you're experiencing. Will idle but not take throttle well. If this checks out I'd still pull the recoil housing and clean the pick up coil and flywheel along with checking resistance on the pick up coil. Resistance should be around 97 ohms.