I had a discussion with a friend of mine over liquid vs. air cooled at the bar last weekend. I would like to hear some other riders thoughts. My friends qualifications are a B.S. and M.S. in Mechanical Engineering from U of M [xx(] in Heat and Mass Transfer so usually agree with him on these matters. Here goes. He claims on a 2-stroke motor the fan-cooled engine will last as long as the liquid under normal operating conditions. He claims to have seen studies using thermocouples across both engines and the variences were negliable under "Normal Conditions". He also rides an XCF (fan) with about 4000 miles and no rebuilds. He claims the only advantage to liquid cooled is less drag on the motor from the fan resulting in more horsepower. WHAT ARE YOUR THOUGHTS?? I would love to prove him wrong.. The only thing I have on him now is a nicer Lawnmower.