Unlike cars who have long graduated from using air cooled engines, many motorcycles still use air cooled engines – even the brand new models (though not many). This is the case because air cooled engines have much lesser parts and are cheaper to build.
If you are thinking of getting air cooled motorcycles, then yes. Air cooled motorcycles tend to overheat quickly – especially when you are idling at traffic. This happens because air cooled engines use the movement of air to cool down.
When overheating, it gets very uncomfortable for the rider and your motorcycle will lose some power. Typically, as you leave traffic and resume riding, the air circulation improves and your motorcycle will cool down again.
Although air cooled engines tend to overheat more than liquid cooled, they are not the only reason why your engines may overheat!
In this article, I will discuss air cooled engines, how they work, how you could reduce overheating and other reasons why overheating can occur.
Doesn’t matter whether you are a beginner or experienced rider, you will definitely learn something new today – so read on.
How Do Air Cooled Motorcycles Work?
Let’s start by briefly discussing how air cooled engines even work. You don’t have to know great details to understand why they overheat.
Like the name suggests, air cooled motorcycles use nothing more than outside air flow to cool down its engines.
Typically, air cooled engines have fin-like openings on their body to allow air from outside to enter. As you ride and pick up speed, air flow increases and enters your air cooled engines through the fins to cool it down.
Air cooled engine have “fins” to allow outside air to enter and cool itself down
This approach is more traditional and easier to maintain. It does not need additional equipment like radiators, coolant and water pump to work (which means less stuff that could break).
You typically see air cooled engines on older classic, cruising bikes like Harley Davidson and Honda Rebel.
Whereas water cooled engines are usually equipped on new and performance oriented bikes like the Kawasaki Ninjas.
Water cooled motorcycles like Kawasaki Ninja doesn’t have fins to allow air to enter
Why Do Air Cooled Motorcycles Overheat?
Air cooled motorcycles tend to overheat for 2 reasons:
- You are idling during traffic
- The weather is extremely hot
Let me explain.
Like we just discussed above, air cooled motorcycles rely entirely on outside air flow to cool down its engines.
When you are riding at high speed and there are lots of wind blowing, then your air cooled engines are fine – air flows will seep into the engines through the fins and cool them down.
However, if you are idling, there’s no air flow – which means your engines are not being cooled at all. And what do you think will happen? Engine temperatures rising up!
Overheating also happens when the weather is extremely hot. Instead of getting cool air, your engine is getting hot air. This will not help much in cooling down the engine.
Things get even worse when you overwork your motorcycles by constantly revving it with high RPM.
Full Reasons Why Air Cooled Motorcycles Overheat (& Prevention)
Of course, air cooled engines are not the only reason for motorcycles overheating. In most cases, air cooled engines will heat up when you idle – it’s uncomfortable but still tolerable.
It’s just heating up though. I wouldn’t call it overheating. Constant overheating of your motorcycles is probably caused by something else. Here are the possible reasons (specifically for air cooled motorcycles)
1. Constant Revving
When you constantly rev your engine at a high RPM, you are overworking your engine. If you are guilty of this, then I suggest you not do this often.
Aside from just overheating, constant revving could cause other damages to the engine parts due to extra pressure, heat and accelerated wear and tear.
Not to mention, your fuel economy will also be impacted. Revving at high RPM consumes much more fuel (and not always generates more power).
2. Improper Oil Circulation
In air cooled engines, the engine oil also acts as a coolant. When room temperature oil flows through your engine, they help to absorb some heat from the engine. It’s not designed for this but it helps a lot.
If your engine is constantly overheating, then it’s possible that your engine oil is not circulating properly. It’s probably time to change that engine oil into new and shiny ones.
Engine oil that’s been used for a while will accumulate dust, debris and other particles. This causes them to clump and not circulate properly.
If you recently changed your engine oil and still have the overheating issue, then it’s likely not because of improper air circulation (don’t bother changing the oil again is what I am saying)
3. Engine Running Lean
Engine running lean means you either have too much air in the combustion chamber or too little fuel – causing your motorcycle to lose power and overheat.
To generate power, motorcycle engines use a mixture of air and fuel to create combustion (which is hot!) Fuel molecules inside the combustion chamber can help to absorb heat – helping your engine to cool down
If there’s not enough fuel, then there’s not enough molecules to help absorb that heat – causing your engine to potentially overheat.
This works well in theory. However, in practice, your engine won’t immediately overheat just because you are running a little lean.
So I wouldn’t assume your overheating issue is 100% because of a lean engine. It could just be a contributing factor.
If you do find yourself running lean, then the obvious fix would be to correct it by getting an ECU tune or get a bigger carb.
I have an article here where I discuss more about tuning. How Much Does It Cost To Tune Your Motorcycle?
4. Clutch Slipping
Clutch slipping is when your motorcycle clutch disengages by itself – preventing your motorcycle to deliver the power required to move forward.
Clutch slip can cause overheating because your motorcycle engines will now have to work harder to provide you that power.
If your clutch is indeed slipping, then you have no choice but to get a replacement (about $450).
To prevent clutch slippage, I suggest you don’t overwork your motorcycle by constantly revving it at a high RPM. Also, don’t engage and disengage your clutch too quickly – this accelerates the wear and tear damages.
5. Engine Misfire
Although quite rare, engine misfires in motorcycles can also cause overheating.
If you don’t already know, when a combustion occurs, a piston inside your motorcycle will be pushed down to generate kinetic energy for movement.
When an engine misfires – combustion occurs at an incorrect timing. If the combustion happens when the piston is going back up, then it’s actually fighting against itself – causing uneven heat spots around the piston.
In the worst case scenario, your piston crown could be burned – causing your engine to misbehave and overheat.
Do Air Cooled Motorcycles Have Limited Range?
No, air cooled motorcycles do not have limited riding range. When constantly riding without stopping, then air cooled motorcycles are great. There’s enough airflow to keep the engine running smoothly.
However, air cooled motorcycles suffer from heating issues when you are at a stop-and-go traffic – think of bad traffic.
In this scenario, air cooled motorcycles should heat up and make it uncomfortable for the riders. But not bad enough until it’s unbearable.
Do Air Cooled Motorcycles Lose Power When Overheating?
Any motorcycle will lose power when overheating – not just air cooled motorcycles.
This has something to do with how combustion engines work. Motorcycles use a mixture of oxygen and fuel to generate combustion.
Hot air is less dense and contains less oxygen – which means your combustion won’t be as powerful. You might even experience bad fuel economy because not all the fuel can burn – causing the unused fuel to exit through the exhaust pipe.
Conclusion
To conclude, air cooled motorcycles do heat up when you are at a stop-and-go traffic. However, it won’t overheat to the point it’s unbearable. (Actually, this heat tolerance depends on you. Might wanna try your friend’s first).
The reason why air cooled motorcycles heat up is because they use the natural air flow from outside to cool down its engines.
When you stop, there’s no air flow – causing your engine to heat up. When you are constantly riding, there won’t be any heating issue at all!
And no, there’s no limited range for air cooled motorcycles. As long as you keep the airflow coming, the engine won’t heat up.
