It has been driving me crazy for almost as long as Ive owned this bike a buzzing rattle like the fairing is loose or a bracket is vibrating at certain rpm. Today while cleaning I was wiping down the radiator end caps and I heard a little clunk like something was loose so I started to tap the radiator with the palm of my hand and I heard it again only louder, so I figured that a mounting bracket must be loose. Everything was tight but the noise continued, finally I noticed that the fan has a little curved cover over the back that just snaps into place and thats whats buzzing. I removed it and the noise stopped YEA! I guess its their to create more suction for the fan while the fan is running but Ive had many watercooled bikes over the years and none have had a cover over the back so I bet it will be OK.