Same here, I took mine out on the last rebuild, now occasionally there is a Humming noise from the Fins. Apparently when Yamaha made the engine, it was (and is) the fins are at an angle to the forward direction of the bike. making the noise more prevalent. With that said, Are you really going to worry about that little noise when your at WOT, I don't think so. (I have yet to start working on my bike since the latest break down)