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All motorcycle engines have a cooling system to deal with excessive heat – either through air-cooling or liquid-cooling.

Each type has its strengths and weaknesses – which this episode is all about.

Tune in to discover:

  • How an air-cooled engine and a liquid-cooled engine works, respectively
  • Some pros and cons of each type



Hello, and welcome to another episode of 30-minute motorcycling – a podcast where you’ll learn about how your motorcycle, moped, or scooter works – in less than 30 minutes.


Did you know that your motorcycle’s engine can get as hot as 100 degrees Celcius or 212 degrees Fahrenheit?


Granted, that’s the ideal operating temperature, but even so, every engine needs some way to get rid of any excessive heat to reduce wear and tear


That’s why every internal combustion engine has a cooling system, which is either air-cooled or liquid-cooled. 


But what are the differences between the two?


In this episode, we’ll talk about the differences between air-cooled and liquid-cooled engines, and some pros and cons of both types.


Let’s begin with air-cooled engines. 


As you may have figured out already, air-cooled engines are cooled with air, which is let into the engine through a series of fin-shaped vents located on the outside of the engine. As you ride, air will flow into the engine through these fins, and cool the engine down.


The benefit of air-cooled engines is that they require less maintenance and have a much lower running cost. 


For one thing, you don’t have to buy any kind of cooling liquid separately, much less top it up or replace it. 


And with no cooling liquid, there’s no need for a water pump or water jacket to circulate the cooling liquid through the engine – making the bike much more lightweight.


It’s therefore common to see air-cooled engines on smaller motorcycles and mopeds.


There are some motorcycles with powerful engines that use air-cooling, although they often supplement it with oil cooling.


So far, air cooling sounds like a great deal – however, the fatal flaw of air cooling is that if your bike’s standing still (such as when you’re idling at a stoplight), there’s no air going into the engine, and it won’t cool down. 


Because of this, most motorcycles use liquid-cooled engines, which are cooled by a type of liquid known as “coolant,” which consists of 50% water (more specifically distilled water) and 50% anti-freeze.


The coolant is then circulated through the engine by a “water jacket” and a water pump. 


The biggest advantage of a liquid-cooled engine is that it works when the bike’s moving, but also when it’s stationary.


However, a liquid-cooled engine requires extra components to work properly, including


a water jacket, 

a thermostat, 

A radiator 

and a water pump


These components and many more add weight to the bike. The coolant also has to be bought separately, which is another expense. 


Also, just like brake fluid, the coolant has to be flushed and replaced once every other year.  


And that’s an overview of the differences between air-cooled and liquid-cooled engines.


If you’d like to know more about engine cooling, including how “forced air-cooling” works, and whether car coolant is the same as motorcycle coolant, I’ve included a link in the show notes to a blog post on The Dual Wheel Journey on the topic. 


If you have any further questions about engine cooling, or if you have a suggestion for a topic that you’d like me to cover, please send me an email at


Until next time, keep your helmet on and your eyes on the road. Bye!