As a person who recieved his BSME degree I feel I do understand physics. No my cht are not 200F they are 160 until I get on it and they will go up to about 180-190. The sensor is on the back of the head and my engine is a gen 1 sbc, so the head is the last thing to be cooled. I don't run a thermostat on this engine, just restrictors in the housing. Yes there are issues running too cool, mainly the oil, this is why I have a high quality sythetic, so it doesn't make acid like conventional oil. Colder air allows me to run more fuel, the more oxygen I can get in the cylinder the more fuel I can pump in, a stoichemetric ratio is 14.7:1 that will not however make more power due to the inability of the engine to make a perfect burn.

That is all off topic though, and still you cannot compare a fullsize water cooled engine to a r/c engine on temps, other comparisons yes, temps no. Fuel is the cooling factor for his OS 2 stroke, fuel has nothing to do with cooling on a 4 cycle water cooled engine, it is the oil and water that cools.

That OS should run about 200F, just as BH said.