I had my 450 apart for a couple of weeks, I put new muffler, plastics, tank and air filter on it. I also put a Dr.D hot start on which involved removal of the carb. Anyways, got it all back together and it ran fine, other than a rare drop in RPM while holding the throttle at a steady opening. It didn't happen all the time, and I didn't think much of it. Today was the first ride, everything went well for 10-15 minutes or so. At this point I was riding down a fire road, hit a couple of puddles from the recent rain. The bike started popping on decel, I pulled in the clutch and the engine died. Let the clutch out and it fired back up, only to continue popping. Stopped on the side of the road for a couple minutes, then tried to re-fire. No luck. Pushed the bike all the way back to the truck and let it sit for 10 minutes, maybe 20. It fired right up. Ran it around the truck for a few minutes, got real aggressive with the throttle. It ran flawlessly. In any case, I'm thinking maybe I have an air leak. Carb? Pipe? Just seems weird that it's intermittent. I had a similar problem earlier this season and my headpipe turned out to be a little loose. I haven't had a chance to check it yet, but could that be the culprit again? Perhaps water from the splashing of puddles got in there?