My freinds ultra 680 won't rev above 5500 for some reason. we just had the motor completley appart down to the crank. The carbs are all fine, jetted to slp spec. It has slp pipes. When it was on the stand it was fine, but he took it accrost the grass and it wouldn't get above 5500. He said it spiked to 6000 once for a second and the bogged back down. I beleive it is supposed to rev to 8700? Can somebody please help me?