I have an 2005 650R (uncorked w/ edlebrock carb)and when I got it the engine ran smooth and clear. The bike only had 250 miles on it. The valves were adjusted at that time. I have put on another 800 miles and I adjusted the valves and checked and rechecked them. I don't have the book so I guess it could be that I adjusted them wrong but I have worked on xr 600rs for years and understand how to adjust valves. The problem is this, when I rev the bike about 50% there is a noticable buzzing coming from what I would think is the top-end. I took it to a mechanic friend of mine and he said not to worry about it. Well I am worried only because it did not make that noise before and I adjusted the valves because I started to hear a slight buzz. I can hear the Buzz while riding at high revs and it is driving me crazy. I keep thinking that something bad could be happening to the bike. any ideas. Does anyone else have these same symptoms?