I have a 01 wr with yz timing and pipe/silencer. I took my bike to get it all greased up and check it out, all warranty work.I get it and they put a knew top end in. no charge, o.k.. I have a 100 mile race in 3 days. Take it out to break-in. alittle poppy on the let off. Then it felt fine.Go to race first set of hoops I hit it starts to bog then I chill out on it let it clear start hiting it hard again starts loading up again 100 miles of frustration. This has happened before I dropped the pilot jet 1 and leaned my fuel screw great. let yamaha have it for a day awfull. help me so I can have a plan b if they cant figure it out!!!!!!!!!!!!!!!!! Thanks guys. P.S. come to a nevada desert race!!!