Again need more info. When running to break in was it running very rich just rich or lean. What fuel? High throttle, or where? From what you said it quit when you pinched off fuel line. This of course would make it very lean and if already running lean it probably overheated badly.Proper break in is to run rich at full throttle then vary needle setting from time to time to allow it to run rich and cool off. After several tank fulls you could try varying throttle setting on occassion. Sounds like you cooked it bad or broke crank.