Thanks Barton, you are my hero also. I have the same problem but not as severe (05 YZ250F). Barely noticeable in the summer but now it feels worse even with proper warm up. I was getting ready to rip throught he manual but I'll follow the FAQ first. I'll tackle it during deer season (can't ride, yz not fast enough to dodge bullets) after this week end I'll take the newly tuned machine to the woods for a thrashin'.
P.S. I love this bike, I just got back into bikes after a 13 years & this sucker makes me smile. Yamaha did a bang up job!!