I need some help here. My 01 SP 500 HO runs very well most of the time with the exception of running in heavy mud or going up a steep hill. When the engine is under a real heavy load (mud or steep hill climbing) it sounds like it's an 8 stroke. The engine is probably getting hotter than usual caused by the heavy going but what could my problem be? My dealer is baffled too.
Your help would be appreciated.

 

What does an 8 stroke sound like ?

 

probably like a diesel...