I have read many of the threads about noisy KDX's (rattles, knocks, etc.) but almost everyone mentions that the noise is heard at idle. I have a 2002 220 and it is quiet at idle but a loud rattle occurs at the mid to upper rpm level, especially when I let off the throttle. It started shortly after break-in and got louder. It is definitely not a clutch noise. I inspected the piston and cylinder - everything is fine. The loose play in the KIPS valve seems the most likely cause but is this common for new KDX's? Would cleaning the KIPS make a difference ?