I'm having trouble with my 500 and I'm not sure if I have an engine or clutch problem. My sled accelerates fine however, after it reaches full shift and you let off the throttle and hit it again the RPM falls and does not climb back up. Sled feels sluggish and feels like the engine is loading up, then after about 10 minutes it fouls the spark plugs. I've replaced the spring in the secondary and cleaned both clutches numerous times afterwards the sled works great for about 15 minutes of trail riding, then the problem comes back. Things to note, my engine compression has dropped from 150 - 120 even on both cylinders, and while riding over some drifts my secondary did not back shift and was stuck all prior to replacing the secondary spring, also my primary clutch gets extremely hot, the belt is brand new. Does anyone have any ideas on where I should look?