When revving the motor while the clutch is pulled in, there is no strain on the motor. So the gain from water circulation and a little air flow through the radiator greatly outweighs the loss from extra heat generated from just "dry" revving. Imagine how must friction there is on the piston/sleeve when the rod angle is at its greatest and you are at WFO in the ever-power-robbing sand. Now take away the load and most of the friction would die.
I concur totally with Backcountry. On my big bore, I usually HAVE to run the bike a little just cruising so it will cool down after a good drag.
Trax310

 

I still would think that most of the heat of generated in the motor is from combustion??? I would be curios to know how much heat is generated from cumbustion, and how much is generated from friction. i am by no means an authority on this, but if your burning more fuel and there are more detonations per minute, i think there would be more amount of heat generated...just my .02 cents. And how much more water can be circulated by jsut revving a little bit more. i would thing that the water is going to reach a balance point with the engine, and then it will simply maintain that temperature especially after a hard run...just speculating though...