I have been riding my 2001 XR650R all summer and have had zero problems with it mechanically. Early in the summer I removed my auto-decompresser because it was acting oddly. I have had over 500 miles without it and no problems. I just moved across Washington 350 miles and had the bike on the trailer. Before trailering it, it ran perfect. I started riding today and it ran prefect until after about 15 miles. It started backfiring (pop pop pop) bad on engine braking. Later the rpm's would drop on idle and it would want to stall. Sometimes after coming off the throttle completely, the rpm's would stay high (up to 3000) and wouldn't come down. Over time it got harder to start. I messed with the throttle screw, but that did nothing for it. It made it fairly difficult to ride because I'd never know when it was gonna idle low/high. I got home and cleaned the air filer. I took the carb off and cleaned the everything from the throttle valve down. I removed the jets and blew them. There were a few dots of dirt in it but I think I caused those when I pulled the carb off. I put it back together and same thing. I've heard the float could be sticky. I inspected it and it seemed to go up and down fine...I don't know what sticky really means let alone how to fix it. I pulled the plug (had some black on it...it came off real easy and a golden brown was underneath) and replaced it. I fired it up again and its acting the same. When the bike is on the stand and parked on an slope, it may spill fuel out the overflow. I'm baffled!