I have a ´97 YZF1000R ThunderAce with the same problem. I got it in May 2005 and it drove me crazy. My mechanic told me to put BUCK SHOTS, yes BUCK SHOTS from shot gun shells in the handlebars (he uses BUCK SHOTS in the handlebars of his ´92 Kawasaki ZX11, mint condition--172hp at rear wheel). Fill it to the top and screw the handlebar ends back on. Try to stay with the original handlebar ends because they are heavy and will dampen some of the vibration. Yamaha took the vibration into consideration so they used very heavy handlebar ends. Also use gel handlebar grips (10 US dollars for a pair). THIS WILL WORK WONDERS FOR VIBRATION IN THE HANDLEBARS. At 5000 rpm, the BUCK SHOTS bounce around in the handlebars absorbing the vibration. IT´S INCREDITBLE!!!! Also try to use a synthetic motor oil with your next oil change and lube the chain very well. This will make the bike run smoother. The synthetic motor oil works wonders on the clutch plates. If any of you guys have any performance upgrades, please let me know. sodavis@bellsouth.net.