I have a Radical .21 621p and a week ago I raced in a night race that started at 3:00 and ended into the morning. My motor was running great and the temps were in the 220-230's after every heat. It got cooler as the night went on and during my third heat he stalled. I replaced the plug(os p3) and went to my main and it flamed out three times. I recently tried to start the motor and it wouldn't even try to start. I pulled the plug and the coil was black! Like it had sut on it. I replaced the plug and it started, but it won't run for more than 30 seconds. If I rev it on the box it will stall during a rev of if on the ground during acceleration. I reset the settings on the carb and still get the same results. I was wondering what the glow plug is telling me being black and only lasting 2 5 min heats? thanks