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Air-cooled vs Oil-cooled vs Watercooled - what's the difference?

Watercooled engines are more powerful, but air-cooled engines are bulletproof. Which should you get?

Motorcycle Aircooled Engine

When viewing motorcycles on a website or in person at a dealership, specifications can get quite overwhelming. Potential buyers are provided an insane amount of information, including a variety of terms like horsepower, constant mesh sequential gearboxes, variable valve timing, variable throttle valves, and so much more. However, many future owners out there may be lost in all the technical terms and mechanical lingo without specifics on how this will affect ownership, maintenance, and day-to-day riding.

One such example would be on engine cooling systems. Some motorcycles are air-cooled, some are oil-cooled, and others are water-cooled. These three cooling types are the primary ways an engine can manage heat and temperature, and manufacturers choose to use a specific type of system for specific kinds of motorcycles. Knowing your cooling system can be a big help when it comes to expecting how a motorcycle will ride, how maintenance might turn out, and what it all means for day-to-day ownership. Here’s all you need to know about motorcycle cooling systems.


Aircooled Engine

When a motorcycle generates heat through the combustion process, excess heat inside the engine must be expelled in order to keep your engine components healthy. One such way would be to redirect heat straight into the surrounding air, through air-cooling. An air-cooled system can be identified if an engine has cooling fins on the cylinder block and no other cooling components like radiators.

Air-cooled engines are typically cheap to make, and provide an adequate amount of cooling for engines that don’t make too much power—more power means more heat, and advanced cooling systems will be needed for high-output engines. Because of this, air-cooled engines are typically found on motorcycles with smaller displacements from the 110cc to 250cc class. Examples of motorcycles with air-cooled systems include the Yamaha XTZ 125 and the Kymco Like 125.

Ownership and maintenance on air-cooled engines are by far the simplest and cheapest. There is no coolant to replace, radiators to inspect, or hoses to check for leaks. However, because an engine will rely on ambient air for cooling, engine oil is typically brought to higher temperatures especially when going on rides with hot or stale air such as an urban commute. Air-cooled engines will most often need an engine oil replacement at shorter intervals, where oil changes are expected every 1,000 km to 3,000 km.


Oilcooled Engine

Oil-cooled engines are similar to air-cooled engines in that cylinder blocks almost always come with a cooling fin design. However, what distinguishes an oil-cooled engine would be the addition of an oil cooler—a radiator-type component that is fed with engine oil in order to be cooled by passing air. Oil-cooled engines are often found on vintage-themed motorcycles with engine displacements of 250cc to 1200cc – where power output is relatively high and additional cooling systems will be needed for temperature management. Key examples include the Royal Enfield Himalayan, the Triumph Bonneville T100, and the BMW R nine T.

Oil-cooled engines are definitely a level up from air-cooled engines when it comes to temperature management. However, because oil-cooled engines include additional components, owners will have to be on the lookout for any leaks on the hoses and seals. Despite this, oil-cooled engines are still relatively easy to maintain given that only engine oil will need to be changed regularly.


Watercooled Engine

The last cooling system on our list is the water-cooled system. It is the most modern and arguably the most widely used cooling system in the market today – and for a few good reasons at that. A water-cooled engine relies solely on the coolant and radiator systems of a motorcycle for temperature management. There are no engine fins nor are there any oil coolers present, which means temperature management can be fully controlled by the motorcycle’s electronic system. This allows manufacturers to maximize engine efficiency for reliability, power, and fuel economy.

Watercooled engines, however, will need a bit more attention when it comes to maintenance. Engine coolant will be an additional fluid to change every few thousand kilometers, and the addition of hoses and seals will mean more areas for leakage and potential replacement. Watercooled systems are also quite bulky and complex, meaning that water-cooled motorcycles will typically weigh a bit more than similar air-cooled or oil-cooled counterparts. The air-cooled Honda CRF150L comes in at a featherweight 122kg, while the water-cooled Yamaha WR 155 weighs in at 134kg.

That is not to say, however, that water-cooled engines are undesirable. In fact, it’s quite the opposite. Because engine temperature management is solely controlled by motorcycle electronics, water-cooled engines can be made to perform reliably and optimally regardless of the ride—whether that’s urban commuting, highway rides, or off-road adventures. Because engine efficiency can be maximized, water-cooled engines are also extremely fuel-efficient for the amount of power or displacement. For the rider who will not want to think twice about engine health, water-cooled motorcycles should definitely be your first choice pick.

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