I just bought a used 97 1100 shadow (spirit) with 10k miles.When accelerating I sometimes get a clunking sounds from shaft .It it like im in a to high gear bucking,roughness.I downshift and it goes away.I will be at 35mph in 4th and give it throttle hard and I will get the sensation? Am I in to high a gear?Manuel says i should be in 4th?