After the engine gets up to temp it does not matter how long you drive it. This
does assume that everything is working OK like the thermostat, thermo sensor,
timing and fuel mixture.

Unfortunately the air cooled engine has no direct way of providing any extra
cooling after it is at operating temp and full load. Water cooled engines could
switch on the cooling fan but this is only a slight advantage.

The only thing I can think of is if the ECU has anything to say about a richer
mixture to cool off the engine. If this is the case then the engine temp is
directly controlled by this small and inexpensive part.
The failure of which is too horrible to ponder.

I know that at low temps the ECU makes the mixture richer. Does it also make it
richer again after the engine gets beyond a certain temp?