I just built a 2004 XR 650 L from the ground up. 10.25:1 Wiseco piston STD bore Hotcam Mikuni TM 38 flatslide Yoshimura exhaust Uni filter Smog removed Airbox opened up Bridgestone ED-77,78 Gritty tires 15-45 gearing IMS 4.0 gallon tank Acerbis DHH headlight Superbrace XR's only skidplate Well the list goes on and on but I must say that the bike works awsome. The motor has alot more power from down low to the top end. It pulls alot harder than a stocker and has a ton of throttle response. I am going to break the motor in a little and then have it dynoed. I think it has to be jetted. It has a TINY backfire when i shut the bike off. Also a little flatspot when the throttle is wicked. Any ideas for jetting? Right now i have a 270 main and 27.5 pilot. I was thinking about a different air bleed.