Have been rebuilding a 1999 Polaris Sportsman 500 with issue after running for 15 - 20 mins it cuts out and will not restart until it is cold. Have been reading about similar issues with this make/model of quads that have starting issues. I have replaced the pulsur coil but problem continues, fuel is ok, has new plug - What else should I be testing or replacing

 

Could be electrical or could be mechanical such as loosing compression when warm. Compression won't show much to begin with because of the decompression device on the cam but should show between 55-90 psi on average. Plus this model fell into the faulty cam problem that a lot had. Check valve clearance along with checking for noticeable wear on the cam exhaust lobe. I'd first go through the stator checks and other electrical trouble shooting steps in the manual to rule out an electrical problem.1999 Polaris Sportsman 500 RSE Service Manual PDF Download Plus when it stalls, check for spark,also pull the fuel line from the carb and crank the engine over. If it doesn't have a steady stream of fuel the pump may be the problem.