What is a normal operating temperature range for the 400ex? I know conditions probably vary this but just curious what is "normal".

 

Measuring oil temperature would be the easiest and most objective way to measure differences between variously moded engines.

This should be easy, just get an immersion thermometer and stick it down into the tank so the oil is just at the immersion line...pretty simple!

I do know that if I pull a big long dune on a warm day, I can feel the engine losing power as things heat up! I run a little extra octane (91 pump gas with Klotz octane booster), so I will not get detonation at such times. Also, being air cooled and because of the head design, I tend to run the thicker oils in my 400 during hot weather.