Ok guys, I presently debate with my brother about cooling on a liquid cooled sport bike.

I said: cooling as to do with the liquid radiator and fan on a liquid bike, Oil as to do with lubrification, nothing to do about cooling the engine transmission ( about this one flame my brother, I don't event know if there is motor oil going in the tranny for lubing or cooling )

Brother said: cooling as to do with oil, your motor oil contribute a lot with the cooling of your engine and transmission. it goes all around your engine and tranny, then to the oil radiator and then to the engine again. Liquid only Help in cooling, Oil do most of the job!

NOW, no mather who is wrong:
Explain me about the tranny cooling/lube and the engine cooling, I always though that liquid bike were cooled by liquid and the oil was, like in the car, there to lube all the piston/sleeve/ring assembly and then evitate some metal to metal friction wich is really bad.

I used the search option and found nothing, I searched in the next field: motorcycle, archived topic: cooling, tranny, gear, rad, radiator, liquid, clutch, and many more. Though nothing has showed up.

I know I will find an answer here.
Sorry about the freacking long post, but I had to explain the fact.
I am an ex Ninja 500 owner, so no flame about me having never touched a bike.

hope to hear from you soon guys.
kranked

 

This depends a LOT on the bike actually, but let me try to make it relativly generic.

In my experience, you don't hear people say "oil-cooled" bike. Generally, they'll say "air-cooled" and then talk about a potential auxilary oil radiator. The exception to this are some of the boxer-engined bikes. The old BMW's (and derivatives) were straight up air-cooled (BMW 'airheads'). In the early nineties they decided they're 30 year old design needed to be updated (you'd think harley would learn..) so they redesigned the bike with FI and improved oil journals and added an oil cooler (oilheads).

Example: The new Buell firebolt has an awesome oil cooler (I know, because a good friend of mine designed it), but if you check the specs on the bike, they'll say "air cooled".

Generally, the difference between the two is the inclusion of more oil and an oil cooler, or possibly larger oil traces.

Liquid Cooled bikes work exactly as you would expect them too. Heat from the block is transfered to the liquid, pumped into the radiator, and hopefully transfered into the air.

The thing is, both you and your brother are mostly right. The missing link is that, the whole engine participates in the cooling. You can't point your finger at a single thing and say "that cools the bike". Even the most advanced liquid cooled bikes STILL are designed to take advantage of the air passing over the block during movement for added cooling efficency. And, just like in race cars, it's not completely unheard of for a bike to run an oil cooler in addition to their normal liquid radiator.

Now, as to the tranni, that also gets into bike differences. Some bikes have seperate gear oil, while some share the same oil supply. Some bikes have a dry clutch, and some have a wet clutch.

Of the bikes that share the oil supply between the engine and the trani, it's true that excessive trani heat would be transfered to the oil and possibly cooled, but the majority of the time the trani is actually sucking heat from the oil, and not the other way around.

For your EX500, You had a liquid cooled bike with single oil supply and a wet clutch. Meaning, your oil circulated through the whole darn bike. Agreed, it did participate in cooling, but as a part of whole system.

 

excellent, I thank's project_mercy for the great answer, anyone want to add something ??, It was pretty clear and straigh forward.

thank's a lot for fast answer, feel free to add thing you think usefull !!

kranked

 

Most small two-stroke engines are air-cooled. Air flows over cooling fins around the outside of the cylinder and head, either by the natural motion of the vehicle or from a fan. Many aircraft four-stroke engines are also air-cooled; larger engines have the cylinders arranged radially so that all cylinders are directly in the airstream. Most four-stroke engines, however, are water-cooled. A water jacket encloses the cylinders; a water pump forces water through the jacket, where it draws heat from the engine. Next, the water flows into a radiator where the heat is given off to the air; it then moves back into the jacket to repeat the cycle. During warm-up a thermostatic valve keeps water from passing to the radiator until optimum operating temperatures are attained.

Four-stroke engines are lubricated by oil from a separate oil reservoir, either in the crankcase, which is a pan attached to the underside of the engine, or in an external tank. In an automobile engine a gear pump delivers the oil at low pressure to the bearings. Some bearings may depend on oil splashed from the bottom of the crankcase by the turning crankshaft. In a two-stroke engine the lubricating oil is mixed with the fuel.