I had the strangest experience today with my 1997 XR600R, and I'm hoping someone has some ideas, because I'm stumped. Just some background... The bike is well used, but has a fairly fresh top end and a few mods... hotcam, Mikuni flatslide, pipe... It has thus far been very reliable, and usually cold starts on or before the 3rd kick, even in cold whether. Today I hauled it to my local OHV park in the back of my pickup. When I got there, I cold started it (60 degrees out) before unloading from the truck (just in case). It started easily on the 2nd kick, as usual. I let it run for a minute and then rolled it off the truck while running. I left it running on the ground for about 5 minutes to warm up while I packed up my ramps and gathered my riding gear. I then shut it down. About 10 minutes later, after getting ready to go, I got back to the bike. It started right up, as usual. I revved it a few times to make sure it was ready to go, and I began to drive off for my ride. I moved about 2 feet before the bike stalled. It felt like the kind of stall that happens when the bike isn't warm enough yet (after a cold start) and isn't quite running right. Once I loaded the engine, it stalled. When I tried to start it again.... nothing. I spent an hour trying to get it running before packing everything up and heading home, very pissed off. Here's what I did, other than kicking a hundred times with no success.... 1) Kicked a bunch of times, gave it a 5 minute rest, and went back at it. 2) Checked the fuel... full tank, gas was "on", full carb. 3) Thought it might be flooded... tried starting with wide open throttle with no success. 4) Turned off the gas, drained the carb, kicked through a bunch of times, and gave it a good rest. Then turned the gas back on and tried again.... nothing. 5) Changed the spark plug and confirmed a good spark. The plug smelled like gasoline, but wasn't wet... no luck. 6) Checked my kill switch and confirmed it was working. (no spark at the plug when the button was depressed, and spark when I let go). 7) Adjusted idle screw for faster idle... nothing. 8) Even tried the choke, which I have never needed before, even in freezing whether. 9) Kick, kick, kick!! Thought my leg would fall off. I got a few pops here and there, but it never fired up. 10) Swore profusely. Any ideas? I tried again when I got it home with no success. Obviously there could be other causes for a bike not starting (carb adjustments, dirty air filter, valves out of adjustment), but I have a tough time believing that these things could change so dramatically from one minute to the next that the bike would go from running fine, to not running at all. In my experience, carbs don't un-adjust spontaneously, filters don't clog instantly, and valves come out of adjustment gradually over time. Why would it start right up when cold, and then when warm, and then not at all a moment later? I appreciate any ideas you all might have. Thanks!