I just bought an 03 1600 Classic. The bike runs great, plenty of power but the motor sounds like a an old pea picker. It rattles when idling and smooths out when cruising. When I twist the throttle hard I hear something that sounds like piston slap. None of this seems to be getting any worse as I ride. I have heard that Kaws traditionly have noisy engines. Whats making the noises that I hear.