I hear ya but water cooled and air cooled engines are apples and oranges. Water cooled engines run thermostats to assure a more constant working temperature which is why water cooled engines run more consistent power levels than air cooled engines do. Air cooled engines must have air passing over the cooling fins otherwise the cylinders gets hot and the running temperatures become more inconsistent too. This doesn't mean an air cooled engine will run at 195* either since if its running in a 195* environment it would quickly overheat because dissipation temps would be even higher and the working temps would be outrageous.
All engines are generally OK up until around 140* ambient temperatures and then it just becomes too hot for optimal combustion, heat dissipation, and oil temperature dissipation for everything to work properly. Diesels will actually work in hotter temps than gasoline engines will but nonetheless, I think I'd rather try to and keep my generator from having to run at maximum operating temperatures since reliability and longevity is what I'm after.
