Generally, the manufacturers have tested, and determined the ideal temperature the engine needs to be efficient. The themostat will allow the engine to warm up to running temp quickly, and to maintain that temperature.
It will not keep the engine from overheating. That indicates a problem that needs to be corrected.
Using a temperature lower than recommended will sometimes (depending on the engine), keep the engine in a cool running mode, ordering richer mixtures than ideal, and possibly retarding the timing.
Removing the thermostat is old technology, when engines were not so tightly controlled by a computer. The Carbs didn't know what what was happening anyplace in the engine (systems), so we got away with it, to some degree. Not so today, I'm afraid.
Advice: Better know what you are doing before trying to outsmart the computer.
Good racing.
Bill
Colder termostat? 
