Do Motorcycle Radiator Guards Cause Overheating?

Should you use a radiator guard to protect your radiator from damage caused by road debris hitting the radiator, and will it affect the running temperature of the motorcycle?

Yes, radiator guards can affect the running temperature of your motorcycle by a few degrees. You can overcome this temperature increase by using a recommended coolant without water.

Do you need a motorcycle radiator guard?

Well, if you have ever picked up a rock on your travels and it’s smashed through your radiator, you will know the value of a radiator guard.

Most of the time, you don’t need a radiator guard when driving on asphalt roads, but then comes the occasion when you have some on the road flip up and puncture your radiator.

You may think it’s no big deal, a bit of lost riding time and a radiator repair, nothing to worry about, right?

Until you find out a quick repair is around 50 pounds, and if you need the core repaired, you are looking at a starting point of 200 pounds, and the price can escalate dramatically.

When you think you can buy a radiator guard online for around 50 pounds and then a little time fitting it.

The radiator guard becomes far more attractive and makes economic sense.

If you take your motorcycle off-road, then it’s a no-brainer to fit a radiator guard. The last thing you need is to be recovered from a track with a broken radiator.

If you are a seasoned rider, you will know it is unavoidable to find debris on the road. Some of the debris has fallen off heavy vehicles by accident. No matter where the debris is from, it is a hazard to a motorcycle rider.

What can cause a motorcycle to overheat?

Many factors can cause a motorcycle to overheat. One could be the total loss of coolant from a radiator with a hole in it from making an impact from road debris.

Running lean

More commonly, your bike runs lean, with not enough fuel entering the combustion chamber. This causes an extended dwell time of the fuel and air mixture, which causes the motorcycle to overheat.

Another scenario is for the ignition to be too far advanced. This rarely happens, but you will have fuel entering the combustion chamber before the piston has reached its full upward stroke.

The fuel ignites at the wrong time, causing the engine to overheat.

With modern bikes, these two overheating scenarios are negated by using a self-learning ECU that can adjust the mixture to match your riding style.


If your bike is overheating with modern bikes, it is invariably a problem with the cooling system, such as a sticking thermostat.

A problematic thermostat may not trigger the fan as your engine gets hotter. If this is the case, your engine will overheat and could be damaged.

In this scenario, you are likely weaving through traffic or stationary. The engine will cool once you move, and the air flows through the radiator.

The problem becomes worse. As your bike’s temperature increases, it will run less efficiently and burn more fuel exacerbating the problem of overheating.

Coolant level

It may seem a simple fix, but how many of us are guilty of not checking fluid levels regularly, we tend to rely too much on the gauge cluster for information and ignore maintenance basics.

The low coolant level will cause your motorcycle engine to run hot for obvious reasons, so maintenance checks are essential regularly.

Many coolants are meant to be used without water. If you dilute the coolant, your engine will run hotter as the cooling properties of the coolant have been diluted.

Radiator core

Radiator cores are made of soft material which aids in heat dispersion; you can always see radiator core fins bent, probably during cleaning with a pressure washer.

When you clean your radiator of all the crap and bugs you have picked up, use soapy water and a soft brush and not a power washer.

Remember that your radiator is made of an alloy with heat sink properties, so damage will change the heat transfer characteristics.

Is it normal for a motorcycle engine to get hot?

Your motorcycle engine is burning fuel in the combustion chamber, and depending on the type of motorcycle, your exhaust header can reach 750 degrees centigrade in normal operating conditions.

Your bike will run around 350 degrees centigrade at the head if you run a cruiser.

Your engine’s temperature must be hot before the throttle is opened fully.

The heat helps the oil do its job and lubricates the minor parts of the engine.

Modern bikes are compact in how the air flows around the engine. This increases the heat of the bike. The alloys used in modern bikes have superior thermal dynamics, but the bike still gets hot, and it is easy to pick up a nasty burn.

Some bikes run hotter than others; road bikes are usually quite cool compared to an enduro that runs very hot due to its design and capabilities.

Heat is a feature of any combustion engine, and although the heat is dispersed through the radiator, the engine will always be hot when running.

Is radiator cover necessary?

It depends on how often you use your bike and what type of riding you do. If you are a fair-weather rider, then it’s probably not worth the hassle of fitting a radiator cover.

If you are a daily rider and your motorcycle is your primary means of transport, then it’s worth considering fitting a radiator guard.

Compared to a new radiator core or repair costs to the radiator core, the radiator protector can pay for itself very quickly.

If you ride off-road, it seems like essential equipment to protect your radiator.