Oil Cooled and Air Cooled motors: Differences

[oops-sorry]

can someone (or a lot of people) explain the oil cooled engine concept. im use to the regular engines that are using antifreeze. is it o.k. to let this bike idle for a while or will it overheat? in town riding? stop and go traffic? traffic jams, such as wrecks where you are only moving about 2-3 mile per hour?

are there any other bikes that are oiled cooled?

[The CyberPoet]

Re: oil cooled engine?

can someone (or a lot of people) explain the oil cooled engine concept.

There are three basic cooling systems used in bikes:

WATER COOLING (antifreeze as your put it) - Primarily using an water & radiator(s) as the method of shedding excess engine heat produced. Used in most modern higher-performance bikes, it limits the maximum temp the engine can get to [before the water boils away, anyway]. Oil temp for the most part is limited to somewhere close to the maximum the water temp can reach, because the water is responsible for carrying most of the heat away.
Advantages: lots of heat-removal capability, which means the ability to use higher compression ratios and produce more power in smaller spaces. Overheating means above about 225 degrees F (pressurized system) or 212 degrees F (unpressurized system); overheating temp drops as altitude goes up. Engine can also use less oil because it merely lubricates rather than also cools.
Disavantages: extra mechanical complexity and more parts that need replacement on schedule: water pump, radiator, hoses, thermostat, fan(s), overflow tank. Care must be taken if the system is exposed to freezing weather (anti-freeze or drain the cooling system). If the cooling system overheats, it generates steam which can easily warp heads and in some cases cylinder banks, meaning a very expensive repair or new engine requirement. Similar problems if a full cooling system freezes it's contents.

AIR COOLING. Basically the engine is finned and the fins are exposed to the air, providing all the cooling for the engine.
Advantages: no added maintenance requirements for cooling system, extremely simple to design, few parts to go wrong unless it overheats (overheating generally means over 380-440 degrees F depending on the oil and engine). Overheating unlikely to cause permanent damages if oil is replaced in short order after overheating. Engine parts generally expand at the same rates by sharing the same temps, increasing reliability. No worries about freezing weather if you can get the fueling to work right (i.e. - if the carbs don't freeze up).
Disadvantages: combustion pressures and total power need to be quite low to be able to shed all the heat well from the surface area of the engine, and surface area vs. combustion area ratios must be respected (usually only found in 1 and 2 cylinder engines as a result). Bike also usually needs to be "naked" (no fairing around the engine) to get the heat out properly. Tends to get very hot (possibly overheating hot) if left standing still (while running) for a long time.

AIR-OIL COOLING (sometimes called oil cooling incorrectly). Primarily using an oil radiator to cool the oil as the method of shedding excess engine heat produced.
Advantages: no added maintenance requirements for cooling system, very few additional parts required, little mechanical complexity (oil radiator, hoses, slightly bigger oil pump), can produce significantly more power than an strictly air-cooled bike. Long-term reliability increases because virtually all engine components heat up identically (since the oil circulates everywhere, the metals come up to temp at the same time). Extra oil used in such systems increase total lubrication reserve. No worries about freezing weather if you can get the fueling to work right (i.e. - if the carbs don't freeze up). Can be packaged with the engine surrounded by fairings because of the radiator reducing the reliance on air moving over the engine for cooling (air moving over the radiator is a different story). Overheating unlikely to cause permanent damages if oil is replaced in short order after overheating.
Disadvantages: Can not cope with the same amount of heat production as water-cooled engines, so compression ratio and total power production is limited. Few warning signs if overheated (overheating generally means over 380-440 degrees F depending on the oil and engine) until failure. Tends to get very hot (possibly overheating hot) if left standing still (while running) for a long time. Requires more oil than comparable water cooled engines.

is it o.k. to let this bike idle for a while or will it overheat? in town riding? stop and go traffic? traffic jams, such as wrecks where you are only moving about 2-3 mile per hour?

In general, no, it's not wise to sit in traffic that is not moving for extended periods of time with the engine running. How long it will take to overheat depends on a wide variety of factors, from ambient temps to how lean your bike is jetted (and whether you are running an ignition advancer). If you are coming down from running 75 mph on the highway for an extended period and hit a traffic jam, you could overheat in as little as four minutes on the Kat if standing still. Unless you have an oil temp gauge (I sell them for the Kats), your first warning that it's overheated is climbing idle RPM, followed shortly by rough idle or possibly knocking. Shut down immediately and wait 20 minutes, or take an alternative path that will get your speed back up to shed the excess heat (high gear, low RPM is best -- say 30 in 5th).

are there any other bikes that are oiled cooled?

Yes, quite a few. Aside from a ton of smaller engined bikes used the world over (such as most 150 - 325cc engines), the list includes:
Suzuki Bandits prior to 2006;
Many lower-output Ducati engines (including their new SuperMotard and their Monsters for most years);
Some BMW flat-twins...

Cheers,
=-= The CyberPoet