hahah i never over heated i have stage 2 cam and nitrous

 

Water is a better conductor of heat by many times over than air is. For example, you can stick your hand in an oven that's at 220 degrees for a short time, and it's no biggie. Stick it in water that temperature and your skin will be falling off. Or, your body in 20 degree air will be okay for a while, in 20 degree water you will only live a few minutes.

Inversely water will scavenge heat away from a heat source (your engine) much faster than air. This is why a radiator is full of little fins--those are to create huge amounts of air-to-surface contact area to get rid of the heat that the water pulled away from your engine. So your air cooled engine is creating hot spots that the cooling fins are struggling to dissipate heat from especially on hot days and under extreme stress a.k.a. big ol' sand dunes.

So, scientifically, the liquid cooling is vastly superior. But if your EX don't overheat, who gives a rip!?!

 

I have ridden with buddies with water cooled utilities and its actually a pain when they get mud in the radiator. Their fans would run continuiously with no effect and would have to stop and let the machine cool off every mile or two.....................and we're always in the mud!

 

wow...so you are saying if an air cooled engine gets packed with mud it wilL not over heat ?

woodsrunner has the right answer,
liquid cooled stays at a constant temp because of a device called thermostat, as every one of you have it in your car (if you are at driving age)
every engine has an optimum operating temp range around 175-200F varying of vehicle.
optimum fuel efficency, engine and oil life.
eccesive heat will promote pinging (bad) and other problems.
some older air cooled street bikes even seize up or just quit idleing (my kawa 750 did) usually restarted after 15 -20 minute of daydreaming of an other bike in the parking lot :-)

with that said , i just bought an aircooled rancher, but it has a huge fan front of the engine.
you 400EX folks need the weight saving (NO fan) so better keep that puppy moving to keep it cool :-)

 

Anything is possible I guess but it has never happened to me or anyone I ride with that has an air cooled quad but yet has happened to 2 of the water cooled quads. That is my REAL WORLD experience take it for what its worth or don't.

 

One small advantage of air cooled engines - the side and rear cooling fins usually don't get covered
with mud, unless it has been submerged in mud, therefore you have SOME cooling. Whereas if a liquid cooled
engine has a radiator plugged, you get almost no cooling. If they made liquid cooled engines with fins,
you could have the best of both worlds.

PS- A good idea for the air cooled enthusiast is a heat insulator for the exhaust pipe. This is a wrap for the
pipe that prevents radiated heat from the pipe hitting the engine cooling fins and adding heat to it.
When used in conjuction with a motor oil heat transfer additive they have been shown to reduce engine temps
on warm days by by as much as 60 degrees. Reduces the heat on your legs too.

 

To shaddy rescalk more engin heat is lost to air than could ever be accomplished by water. When the engin sucks air in on the loading strock of the four cycle the temp. drop of the cylinder is about 900-1000 degreas. Making this the primary cooling system of all engins

 

On a stock bike you will not notice much of a difference between an air cooled or water cooled engine, but when you go big bore, big cams, big carbs, hi compression pistons you will start to see a big difference.

 

WoodsRuner really has a couple of good post on this subject.
As you try to make more and more power from a given size engine, you reach a point where an air cooled engine will make more heat than it can get rid of.
You saw the change to water cooling in two strokes in the early eighties.
It was possible to build an air cooled two stroke to the same power level but it could not reject the heat fast enough and would not last.
With the new breed of high performance four stroke ATVs, I would imagine they are coming to a similar point.

 

You are right, you couldn't get the horse power out of an aircooled 250 cc twostroke engine that you could get out of a watercooler one. Look at the atc 250r, the watercooled one's where a lot stronger than the air cooled.

Now with these hi reving (10+ K) fourstrokes you will see the same.