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Air Cooled vs Liquid Cooled Motorcycle Engines

Air Cooled vs Liquid Cooled Motorcycle Engines

One of the considerations to make when buying a motorcycle is the difference between air cooled vs liquid cooled motorcycle engines. Depending on where and how you plan on riding, a motorcycle’s air or liquid cooling may play a large part in your decision to buy, and how much you’ll appreciate your machine.

Typically speaking, high-performance motorcycles tend to be liquid-cooled. MotoGP motorcycles, which cost millions of dollars, are all liquid cooled, but then again, when’s the last time you took your bike to a race track? Maybe an air cooled motorcycle will work just fine. Read on to find out the pros and cons of air cooled vs liquid cooled motorcycle engines.

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Air cooled vs liquid cooled motorcycle pro and cons

  • Air cooled motorcycles run noisier.
  • You’ll tend to see air cooled more on cruisers, as most cruisers typically run at lower RPMs then sportbikes.
  • Sportbikes tend to be liquid cooled.
  • Air cooled engines provide more simplicity, representing one less component which could break, need to be replaced, or need servicing
  • Liquid cooling rads are sometimes fragile, and external or aftermarket oil-coolers can also be expensive and could break in an accident.
  • Air cooled bikes may be cheaper.
  • Air cooled motorcycles are likely more feasible for single cylinders (big thumpers), or parallel twin engines.
  • In V-Twins, the back cylinder could remain hotter than it otherwise would.
  • In liquid cooled engines, the circulating liquid evens-out hot spots in the cylinder head. This is better for detonation control and for emissions. The combustion chamber surfaces can be kept hot enough to encourage more complete combustion, but not so hot so as to promote detonation or high NOx emissions.
  • Liquid cooling is better for long-term durability since it allows tighter build tolerances.
  • Liquid cooled engines transfer the heat to the rad at the front of the bike, making a long ride or a traffic grid lock more tolerable for the rider.

Air Cooled Motorcycle Engine

My personal experience on air cooled and liquid cooled bikes

Personally, I switched from a japanese liquid cooled motorcycle, to an air cooled Harley-Davidson. I was a student riding to downtown Toronto, and the bike just got far too hot for me. I switched back to liquid cooling. Of course, I live in the most densely populated city in the country. Your experience on an air cooled motorcycle may be far different from mine. In fact, Harley-Davidson has the largest share of motorcycles over 750cc on the market. The vast majority of their line up are bikes powered by air cooled motorcycle engines.

It’s not about right or wrong, or good or bad, it’s about letting you know what the differences are.

Does a liquid cooled motorcycle engine work well in the winter?

You may also want to check out this story we just did, answering a reader’s question on how well, and how, a liquid cooled motorcycle works in the winter.

Where does the heat go?

About 44% of an air cooled engine’s heat gets blown out of the exhaust. Only about 12% leave through the cooling fins. In liquid cooled motors, the heat is cooled by a coolant liquid, and then released into the air through the radiator, which acts as a heat exchanger.

Some additional notes, from the comments section:

  • Air cooled engines run richer, making them less efficient and more polluting.
  • Water jackets in an engine act as sound insulators therefore liquid cooled engines are quieter than air cooled engines.
  • Liquid cooled bikes can rev higher because they have higher tolerances due to their ability to self-cool.
  • Air cooled require less maintenance and are often associated with simple vehicles.

What you’ll want depends entirely on your ride. Sportbike or other high-revving engine, you may want to make sure you’re getting something with liquid cooling. Scooter or cruiser can probably get away with air-cooling. Many people say Harley-Davidson Sportsters never overheat, but if they do get hot, there are always things you can do, such as switching to a full synthetic motorcycle oil, or adding an OEM or aftermarket oil cooler.

Have other questions?

You might also be interested in articles such as Disk Brakes vs Drum Brakes, or Shaft Drive vs Belt Drive vs Chain Drive. Tap into our library of motorcycle knowledge here, or ask a question in the comments area below!

About Adrian from YouMotorcycle

I started riding motorcycles in 2007, founded YouMotorcycle in 2009, and was working in the motorcycle industry by 2011. I've worked for some of the biggest companies in motorcycling, before going full-time self-employed in the motorcycle business in 2019. I love sharing his knowledge and passion of motorcycling with other riders to help you as best I can.


  1. water cooling on a bike is nonsense. Aircooled bikes don’t overheat

    • I was sitting in traffic at Myrtle Beach. Couldn’t move. I had to pull over and turn off the bike to cool (in 100 degrees no less). It was WAY over-revving. Then, I’d move a little, turn it off, move a little, turn it off.

      • I agree Jim. My old KZ1100 did not like to idle long times either. Air cooled is fine on the open road, but in town traffic. Especially for parades, liquid cooling is better.

    • Air cooled bikes sound like a rattling bucket of nails. Liquid cooled bikes mask the engine rattle with fluid around the cylinders. That’s the diff. Air cooled sound like poop.

  2. Hello,

    Air cooled engines need much richer carburetion to cool them this means they pollute much more than liquid cooled engines. Liquid cooled engines can operate with carburetion set to burn all the fuel in the mixture. This chemical balance is called stoichiometric combustion where all the fuel is burned. Air cooled engines will never run with stoichiometric combustion because they would quickly overheat.

    Water jackets in an engine act as sound insulators therefore liquid cooled engines are quieter than air cooled engines.

    Its inevitable that governments will regulate motorcycle tailpipe emissions which will be the end of air cooled motorcycles.


    • I am with Eric on this. Harley and those who have followed its lead have perfected the air cooled V-twin engine to the extent it can be. They are relatively clean and powerful, but a water cooled bike which allows tighter tolerances will pollute less and rev higher, producing more horsepower. The proof is riding on the road now. Look at the amazing power difference between Harley’s lower displacement, water cooled V-Rod and their larger displacement cruisers.

      I am riding my second Harley touring model and I love it, but I think by the time I get around to getting my next one it will be water cooled and it likely won’t have push rods.

      Jefe Smith

    • No. Government will regulate the types of muffler is used. And fine idiots that enjoy waking the dead with their bukes

  3. musictoone@yahoo.com

    I can’t go back to air cooled. loved my yamahas but liquid cooling has been awesome in the las vegas desert. my vtx has a fan that comes on just like a car to keep cooling even if at a stop light. a few more parts? yes, but way worth it. if I didn’t live in the desert? then air would be fine I think.

  4. Currently own Harley Road King(103) and it gets oppressively hot. I’ve had liquid cooled bikes and never had a problem with heat or cooling parts failure. I’ve got a friend with a 2014 Tri Glide(cooled heads) and they say it still gets very hot. Liquid cooled victory touring bike here I come!

  5. Interesting discussion. Although I have had two air cooled bikes in the past, I had not really thought about the relative advantages and disadvantages in relation to water cooled engines before.

  6. tnx everyone, pls i am new in bike world and i want to get one for myself, please advice me on which to buy, air coolant or water coolant?

  7. One advantage air cooled motors have is easier maintenance, Another advantage the air heads have is looks. I find a nice set of jugs sticking out into the air a thing of beauty! Look at the Moto Guzzi, the older air head BMW’s, Triumph, Norton’s Harleys ect. However if you want to make a lot of power and do it reliably liquid cooled is the answer.

  8. Why is it that air cooled bikes seem to get better mileage than the water cooled ones? Are they just tuned differently?. Check the motorcycle magazine road tests to confirm this. I average 40 to 45 mpg with a Harley Road Glide (103 ci – 1688cc engine) Friends with smaller Yamaha and Honda engines, both V-twin and inline 4’s seem to hover around 35 mpg.

    • First off, long time no see, brother. Welcome back!
      Second, not so fast!! My 800cc Suzuki v-twin averages 41 mpg, and that’s 90% downtown/inner city riding. If I were doing the kind of touring you do I’d be averaging much higher. See fill-ups on my Fuelly.

      • Hey Adrian, you argumentative SOB, I am just back from another cross country ride and I spoke with a lot of riders about mileage. Granted, your in-city mileage is worse than on the open road, but even in the city my nearly double sized air cooled engine never drops below about 37 mpg. Could be that an old guy like me is just more into cruising with an easy hand on the throttle. By the way, no argument about engine heat, but that can be a good thing riding in the cold weather you experience with some regularity.

        • Hey Jefe, try to factor in that on my bike, 1st gear ends around 30-35 km/hr (18-21 mph). On smaller bikes we’re stuck upshifting and downshifting a lot more… Versus when I was riding around on the Harley-Davidson Breakout I almost never had to get out of third gear in the city. Not to mention smaller bikes having to rev more? Just a theory. You could probably compare comparable bikes recorded fuel mileage from links on this page if really curious: http://www.fuelly.com/motorcycle

  9. cat (AIRBORNE III)

    i think harley davidson motorbikes were meant to design as AIR COOOLED ENGINE because they are LONGSTROKE engine,a long stroke engine has a good advantage of making a LARGE TORQUE,but has a less RPM so which mean LESS COOLING that the BIKE NEED.unlike some motorbike engine that has a less stroke OR a SHORTSTROKE has more potetially to produce A HIGH SPEED RPM but a less TORQUE so they need MORE COOOLING .a basic explanation.WHOS with me????

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  14. Riding air cooled takes some attention. Sure, you cannot afford to get stuck in traffic on a hot summer day,. But water does corrode metal, air, not so much. You don’t have to maintain a air cooling system, there’s not radiator flushes. For that matter, there are not leaks either. I’ve owned bot air and water cooled motorcycles. Maybe I’m just old school but all Nine Hells will freeze before I ever ride another water buffalo.

  15. Back in the ’80s I rode my air-cooled ’79 Kawa 1100 XS Special in hot Calif. weather everywhere. Can’t recall a single instance where the engine appeared to get too hot. Great engineering on my bullet-proof inline 4.

  16. cant believe nobody mentioned the weight difference – a liquid cooled motorcycle will weight way more

    • In a car, maybe, but in a motorcycle, you’re not adding all that much weight. In fact, you could argue that air cooled motorcycles are the ones that tend to be built to a price point, so they might be more likely to have heavier, less expensive components. I have a review of a Yamaha XSR 900 coming up. It’s liquid cooled, makes 115 horsepower, and a wet weight under 430 lbs. Find me an air cooled equivalent that can say the same thing. I’d say on motorcycles, the weight difference is arguably a moot point.

  17. Prefiro refrigeração a ar, esses motores são projetados para nunca superaquecer, mesmo sem movimento.

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