Do Harleys Typically Overheat? (Solved & Explained)

Motorcyclists enjoy cruising down the roadway on their bikes, especially when the weather is beautiful.

However, nothing spoils the fun faster than having your bike overheat while you are riding.

Overheating is a serious issue among riders but can be avoided if you take the proper precautions.

How Are Motorcycle Engines Cooled?

Over the years, motorcycle manufacturers have used different cooling systems, ranging from the original air-cooling method to modern liquid-cooling—each with its own pros and cons.

1. Air-Cooling:

The original engine-cooling method is air-cooling and has become common in many types of motorcycles over the decades.

Air-cooled engines rely on natural air to keep the engine cool. As the bike moves, air passes across the cylinder fins and reduces the engine’s heat to keep it cool. The system is simple and very effective.

Air cooling could be compared to the way our own bodies stay cool on a hot summer day. Think of standing on a sidewalk on a hot summer day with no breeze: just you, the sun, and your sweat. You would get pretty toasty.

Now think of standing in the sun with a breeze. That little bit of air movement can make a world of difference.

The advantages of an air-cooled engine are that it doesn’t have radiators, water jackets, or water pumps. That makes them simple machines in regards to operation and maintenance.

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2. Oil-Cooling:

Oil-cooled engines are similar to air-cooled engines, the only difference being the presence of an oil cooler in the former.

An oil cooler is a radiator-like component that uses engine oil as a coolant to remove surplus heat from the engine.

The engine transfers heat to the oil, which then goes through the oil cooler. The cooled oil now goes back into the engine to cool it, and the cycle repeats.

Oil-cooling allowed Harley-Davidson to continue using the air-cooled Big Twin engine on its bikes. H-D’s engineers created a dual-cooling system that used both oil-cooling and air-cooling to reduce engine heat.

This way, oil-cooling could further complement the efforts of air-cooling. Oil coolers are especially helpful in areas that experience hot weather or if your daily commute includes rush hour traffic.

3. Water-Cooling:

Also called liquid cooling, water-cooling is the most common cooling system on modern bikes. Water-cooled engines don’t have cooling fins like air-cooled engines do. Instead, they use a series of passages to circulate coolant throughout the engine.

Coolant, a.k.a antifreeze, is a 50/50 mixture of both coolant liquid and water. The coolant removes heat from the engine, then goes through the radiator, which uses a fan to cool it, and the cycle starts over.

Water-cooling allows engines to operate at a more consistent temperature irrespective of traffic and weather conditions.

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Why Do Harleys Get So Hot?

The reliance on air to reduce engine temperature means your air-cooled Harley will get toasty when air isn’t moving across the engine.

In particular, idling for long periods of time or moving at slow speeds will cause the engine’s temperatures to rise rapidly.

An air-cooled engine has metal fins cast into the cylinders and cylinder heads. As the motorcycle moves, the fins dissipate the heat in the engine. The dissipated heat is then released into the air through an outlet located in the engine.

Air-cooled bikes are more likely to overheat compared to their water-cooled counterparts, but that’s not to say a liquid-cooled bike can’t overheat too.

Since air-cooled engines depend on air movement across the motor to cool the engine, they are more likely to overheat in cases where the air movement is reduced, such as when you’re stuck in traffic or have a strained load.

Although air-cooled motorcycle engines are simplistic and easy to maintain, they are not as effective as liquid-cooled engines in certain circumstances.

For air-cooling to be effective, the bike must be moving with air flowing across the engine. If the bike’s idling for an extended period of time without moving or moving at low speeds, it is more likely the bike can overheat. 

Some modern v-twin bikes are engineered to use air and cooling to keep engine temperature down. This dual-system is what you’ll find on modern Harleys and some Indian Motorcycles.

The dual cooling bikes are not so prone to overheating as the regular air-cooled models.

Harley-Davidson and Ducati have taken steps to phase out air-cooling on their models. Liquid cooling was introduced on Harleys in 2014, and more models are getting liquid-cooled engines.

For now, only a handful of bikes in the Harley lineup use liquid-cooled engines. But it’s quite apparent the case won’t remain the same for much longer.

Harley-Davidson recently filed patent applications for a new 60-degree V-Twin engine, which will be liquid-cooled.

To no surprise, the report stated the new engine would power Harley’s newer models, including the Bronx Streetfighter and the Pan-American Adventure Touring Bike.

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Do Harleys Typically Overheat In Traffic?

The effectiveness of air-cooling depends on one factor: airflow. It is the natural airflow that passes over the fins and cools the engine. Once the air isn’t moving across the engine, the engine can overheat.

Stop-and-go traffic is one of the situations where the airflow across your engine is reduced/restricted. It limits you to low speeds or no movement, making it the bane of air-cooled engines.

When you are stuck in traffic, you are not cutting through the air like you would when cruising. As such, little or no air is passing over the fins. What happens then is that the engine temperatures start to rise. At this point, several things can happen.

Your bike may become hot but not so hot that you can’t ride. On the other hand, the heat could be so extreme that you have no choice other than to stop riding. In some extreme cases, the engine may seize, forcing your bike to stall.

The only way to prevent your air-cooled motorcycle from overheating in traffic is to avoid traffic altogether.

The rate of airflow across the engine is the most significant factor influencing the air-cooling system. However, its effectiveness is tied to the difference between your engine’s temperature and the ambient temperature.

What Causes Your Bike to Overheat?

An overheated bike is preventable if you’re aware of what causes a bike to overheat.

There are a few different factors to consider:

1. Bike Load:

Consider the weight and workload you’ll be putting on your bike. How much weight will you be carrying?

Will there be an additional passenger or luggage on your motorcycle to increase its odds of overheating.

The heavier your bike, the more power the engine has to produce to move it. If you are riding long-distance with a considerable load, be on the lookout for signs of overheating.

The load isn’t just about weight; it can also come down to riding style. Cruising on flat roads puts minimal stress on your engine. Riding in hilly terrain where you have to navigate steep ascents is a different case.

Your engine will have to produce additional power to help you ascend safely. More power equals more heat.

2. Climate:

Do you live in a warm climate like Phoenix, or do you live somewhere a little bit more chilly like Milwaukee?

The climate you live in can make an impact on how efficiently your bike cools.

Your air-cooled bike depends on flowing fresh air to dissipate engine heat. Relying on hot air to cool a hot bike can work, but it’s not the same as having cold air cooling a hot engine.

If the air outside the engine is warm due to increased temperatures, it can be difficult for the engine to cool.

3. Oil:

Clean oil is important—also the weight of your oil.

Whether your bike is air, liquid, or oil-cooled, if you’re running the bike with old oil or the wrong weight, it can reduce the engine’s efficiency, which causes friction, which causes heat.

Are you sensing a trend?

How Can I Tell If My Harley Is Overheating?

The most obvious sign of an engine overheating is a hot engine:

1. High-Temperature Reading

Excessively high readings on your Harley’s temperature gauge are a good indicator that your bike is overheating.

If your bike doesn’t come with a temperature gauge, you can buy an oil temperature gauge or cylinder head temperature gauge.

Both give you an idea of your bike’s present operating temperature and help prevent the machine from overheating.

2. Steam or Water From the Engine

This is perhaps the most apparent symptom of engine overheating. It only happens on liquid-cooled bikes, but if you see steam coming out from the front of your engine, pull over and shut off the engine as quickly (and safely) as possible.

That’s coolant evaporating out of the radiator and can cause more damage to the radiator (e.i, blown water pump) if you keep it running.

Let the bike cool down, and if you can, top off the radiator with fresh coolant.

Otherwise, it’s best to call a buddy with a pickup truck because even after the bike has cooled, there may not be enough coolant to keep the bike running smoothly.

3. Loss of Power

When your engine overheats, you may notice a significant reduction in the bike’s speed and power.

The motorcycle may also become cumbersome or sluggish.

4. Engine Stalling

A feature in newer Harley engines allows them to cut off when internal temps rise to dangerous levels.

Overheating can cause significant problems, e.g., piston seizing, which can destroy the engine. Newer tech forces Harley engines to shut down before damage occurs.

Therefore, if your Harley stalls, ensure it’s not because of high temperatures.

What Can I Do If My Harley Is Overheating?

Once you discover your Harley’s engine is overheating, pull over to the roadside and turn off your bike.

Allow it to cool off for at least 15-20 minutes before trying to ride it again.

Check the level of coolant or oil in the engine. Low levels of either coolant or oil will cause your bike’s engine to overheat.

Ensure the coolant or oil isn’t leaking through an obscure hole. Examine radiators, too; clogged radiators or faulty radiators may be responsible for your bike’s overheating problem.

If you start the bike again and the engine still overheats, don’t ride it. Riding a motorcycle with an overheating engine is dangerous.

The excessive heat could cause extensive engine failure, which is costly to fix.

Calling a tow company to come to pick you up and your bike is cheaper than an engine rebuild.

How Do You Prevent Your Harley From Overheating?

Overheating will not only make your ride uncomfortable; it may damage your engine.

Here are tips to prevent your Harley’s engine from overheating:

1. Read the Owner’s Manual

When you buy a new bike, READ THE OWNER’S MANUAL! It has all the information you need to keep your bike running at peak performance.

Your owner’s manual will tell you everything about your bike, from the right gas, oil recommendations, tire pressure, and load capacity.

You don’t have to memorize your owner’s manual word for word but be well acquainted with you, so you know where to look when you need information.

2. Check Coolant Levels

If your bike is liquid-cooled, ensure the coolant in the engine is at optimal levels. Once the coolant dips below the recommended level, top it off or flush it out with a new coolant if it’s been a while.

Another key factor in keeping your bike running well is to use quality coolant from reputable dealers. Low-quality coolant will not cool your engine effectively and may even damage it.

Avoid mixing coolants in your radiator. It’s fine in a pinch, but it’s best to keep to one kind of coolant.

Having an old or mixed coolant in your engine could gel and create problems down the road.

If you find yourself needing to refill your engine with coolant repeatedly, make an appointment with your local motorcycle repair shop.

3. Inspect the Radiator

While you’re checking the coolant, inspect your radiator and its components as well.

Radiator hoses and gaskets may wear out due to old age and cause coolant to leak out. The buildup of dirt in the system can also create a faulty radiator. In particular, the jackets may not function well if covered in dust and other waste particles.

A bad radiator cannot keep the coolant fresh, meaning the heat dissipation process can’t be completed. If this happens, your engine will likely overheat.

Keeping the radiator clean is an excellent way to ensure proper cooling for your bike.

4. Ensure There’s Always Enough Oil in the Engine

Low or old engine oil will lead to inadequate cooling, especially on oil-cooled motorcycles.

Having low engine oil will cause internal engine parts to grind against each other, causing unwanted friction. Not only will higher friction increase your engine’s temperature, but it can also lead to engine seizure and failure. Can you say: engine rebuild.

Change the oil in your engine, as recommended in the owner’s manual.

If the engine oil is old, replace it with fresh oil. Old oil leaves behind debris that will gunk up your engine and keep the oil from providing the lubricating moving parts, increasing friction.

5. Avoid Stop-and-Go Traffic

Riding an air-cooled motorcycle in stop-and-go traffic can be miserable!

It’s not uncommon to have to reroute yourself or pullover during heavy traffic to prevent overheating your bike and maybe some heat blisters on your legs. Remember, air-cooled bikes depend on moving air to cool the engine.

When you’re sitting or moving slowly in traffic with high RPMs, there may not be enough air flowing across your engine.

As a result, the chances of your engine overheating will increase. This can also happen to liquid-cooled bikes, but not as often.

Even though it’s less likely, overheating in traffic can happen in hot or cold weather.

There’s nothing worse than sitting in traffic in bad weather, so plan your route accordingly. Once it overheats, you’re not going anywhere for at least 30 minutes.

6. Ride Responsibly

Riding at high speeds for an extended period of time means keeping those RPMs high.

This puts a strain on your engine and keeps the engine pistons moving continuously, increasing the engine’s heat. Cruising at a moderate speed is better for your engine as it puts less strain on engine components and stops it from overheating.

In other words, you don’t have to be a speed demon down the open interstate.

Enjoy the ride. You’ll get there soon enough.

7. Activate Electronic Idle Temperature Management System [EITMS] while in traffic

All new Harley motorcycles have an Electronic Idle Temperature Management System [EITMS].

This feature reduces engine heat while idling in traffic by shutting down one cylinder. The EITMS has sensors that monitor temperature levels in the engine.

Once it detects abnormally high temperatures, it will cut off one of the engine cylinders [usually the rear one].

To activate the EITMS feature on your Harley, roll the throttle forward and hold it until the cruise control indicator flashes.

The cruise control indicator will flash green when you enable it and yellow when you disable it.

It doesn’t matter what kind of cooling system your bike uses. There is always a chance of your bike overheating if you are not properly maintaining your bike.

By knowing what to expect from your bike, you’ll be better attuned to when something is wrong and which cooling system can best match your riding style.

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