An engine that runs for a while and quits is not getting hot, it's running out of fuel...Running out of fuel is caused by a clogged filter screen or a leak somewhere in the pulse passage, or a carb in need of a rebuild..
Usually if it gets hot enough to quit you will have some aluminum from the piston stuck on the cylinder wall..It stops REALLY fast when that happens
Pinch off the fuel line and see what happens, it just stops, no harm done...Can't run long enough to get hot and to seize...Pinching off the fuel line is one of the ways we use on Quicky 500s to kill the engine, a u bend in a piece of 1/16 rod pulls the fuel line against the firewall...On the big race plane we pinch off the pressure line to the carb, same thing, instant stop...