Hi guys, I'm having a problem with my '97 sportsman 500. It seems that when ever I open it to full throttle it starts lossing power, and when I let go it backfires. I took it to the dealer and he said it's not the carb., bad gas,or the plug. Any advice? Thanks......

 

Possibly your cam?

 

Rev limiter engaging when it shouldn't?

 

A camshaft going south will start showing first symptoms at full throttle - as the exhaust lobe starts wearimg down the lift on the exhaust valve will reduce - resulting with the exhaust gas not fully being discharged from the cylinder, therefore not letting enough fuel/air mix in on the intake stroke as the excess exhaust is escaping through the intake valve.

From my experience, the camshaft failure signs are loss of higher RPM's, the electric starter will become "draggy" and often kick back, and the rope starter will have so much resistance (compression against it) that it is almost impossible to start by means of the rope.

Something else I've noticed on the older models (96-99) is that if the airbox does not seal good, the additional air being sucked in will cause loss of higher RPMs and backfiring.

 

Hey guys thanks for the advice I will try these tips and maybe, just maybe the'll work.