I have a 1997 Polaris Sportsman 500. I can get it to start, but as soon as I try to give it any throttle, it wants to die. I rebuilt the carb, but it didn't help. I replaced the carb. Still doing it. Checked the fuel tank vent- it's clear. No vacuum leaks, or obstructions in the intake/ exhaust. Have any ideas about this? This thing is driving me crazy, LOL.

 

Couple things you could confirm to help:
1) did you do a compression test? What's the result?
2) There may be an air leak...does it idle high? Does it sputter if you spray carb cleaner around the carb when idling?
3) Have you checked the valve clearance lately? Are both the intake/exhaust valves in spec and opening/closing fully?
4) Could be electronic...there is a reverse override button...it may be malfunctioning and retarding the ignition...try pressing the button to see if you can accelerate...

 

I did the head gasket, and valves, about 250 miles ago, so I really hadn't suspected valve clearance- but you are right, a compression test couldn't hurt. Can't find an air leak. I never even thought about the reversee overide! I will definitely check that out. Thanks!