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What causes motorcycle engine overheat?

Find out how you can prevent overheat from ever happening.

Engine Overheat

Engine overheat is considered to be a more common motorcycle issue that gets the best of riders when it’s least expected. Engine overheat can be troublesome, and getting out of a situation caused by overheat can be pricey. Despite this, many riders out there still get blindsided by the situation and may not know exactly why an engine tends to overheat and what can be done about it. As such, it’s important to know exactly what causes engine overheating, to begin with, and more importantly, how riders can prevent situations like these from happening. Here are five of the more common reasons why motorcycle engines overheat, and what you can do to prevent an overheat situation from happening.

Hard riding

Track Day

One of the most common reasons an engine overheats is due to hard riding. Going through the gears at a high RPM provides an irreplaceable rush that motorcyclists embrace when the road conditions permit. When a motorcycle is tasked to provide an abundance of power over periods of time, an engine has to spin a little bit more and work a little harder to provide the rider’s desired power. As such, engine’s will heat up and can sometimes be pushed beyond designed operating temperatures. Engine overheat can happen when a motorcycle engine is pushed beyond its limits.

In order to prevent this, the answer can be relatively straight forward. Try to keep your motorcycle’s engine spinning at lower RPMs and squeeze on the throttle only when needed. When your engine spins at a lower RPM, and less load is demanded from the engine, temperatures are kept within the operational limits of your cooling system and will be able to keep temperatures at bay.

Faulty cooling system

dirty radiator

When a cooling system is in question, there are many variables that can cause poor cooling efficiency. A malfunctioning radiator fan, a faulty water pump, stale coolant conditions, a dirty motorcycle radiator, and a worn-out radiator cap can all cause your cooling system to run poorer than originally designed, and can cause engines to overheat. In order to prevent engine overheat caused by a faulty cooling system, it’s important to check that the aforementioned components are always in tip-top shape. Inspect your radiator fan’s spin, ensure that the radiator cap creates a perfect seal with the radiator, have your service center inspect the water pump, and attend to a full coolant flush when possible.

Bad engine oil

Bad Engine Oil

Dealing with engine oil can be a tricky subject. Ask any motorcyclist for engine oil recommendations and you will be sure to receive an array of recommendations of different brands, oil viscosities, and base oil specifications. Despite this, it’s always important to follow your manufacturer’s recommended oil specifications in order to achieve the best results. When an engine is tasked to run on oil outside the designed specifications, your engine will have to work extra hard to make sure that oil can properly lubricate the engine.

Engine oil not designed for the engine can escape into the combustion chamber and eat into our oil levels, or can more easily vaporize inside the sump if an engine gets too hot. When oil levels are too low, an insufficient amount of oil will be asked to cool the engine and can preempt engine overheat. The added friction of a different oil viscosity can also cause more friction inside the engine, causing the engine to overheat. As such, the best way to prevent engine overheat caused by bad oil is to ensure that your motorcycle is running within the manufacturer’s recommended oil specification and that your engine always has the right amount of oil inside the engine.

Running too lean

exhaust smoke

In order for your motorcycle to produce power, your engine needs to have a healthy balance of air and fuel to facilitate ideal combustion. From the factory, your motorcycle can create this ideal proportion of air and fuel very naturally. Over time, however, wear and tear from many kilometers of usage can create a deviation from the ideal air-fuel ratio, and can cause your engine to run poorly. Running rich, with too much fuel in the ratio, will actually facilitate cooler combustion temperatures, but this comes at the expense of poor power delivery and carbon build up on the spark plug and on the engine valves. On the other hand, running lean, with too much air in the ratio, can cause pinging noises, poor power, and ultimately, extremely high combustion temperatures.

When an engine’s air-fuel ratio is skewed towards a lean mixture, engine overheat can easily occur. In order to prevent a lean mixture from happening, two things need to happen: either you can introduce more fuel into the mixture, or reduce the amount of air entering the system. For those running carbureted motorcycles, a simple air filter change and a carburetor tune-up may solve this problem. For fuel-injected motorcycles, an air filter change and inspection of the fuel delivery system can solve this problem and bring balance to the air-fuel ratio, allowing the bike to perform as intended.

Hot weather

hot weather motorcycle

Last but not the least, hot weather can very easily cause an engine to overheat. Cool air is always the best remedy for a hot-running engine. This is why engine temperatures can sometimes be cooler when on the highway versus when commuting through city traffic. The consistent breeze of cool air allows engine heat to dissipate into the environment, keeping your operating temperatures at bay. However, our tropical climate in the Philippines can sometimes be counterproductive to engine cooling due to the hot weather. In very hot weather, engines can have a hard time cooling themselves because hot air will not easily dissipate hot engine temperatures, especially during commuting and low-speed environments.

Solutions to this problem are not as straightforward as we would often like, since controlling atmospheric temperatures can’t be easily done by a motorcycle rider. If you will be faced with very hot weather, and a riding environment that will not allow for a consistent flow of air, a rider can prevent overheat by mitigating all possible causes of overheat, to begin with. The previous sections will be of the greatest help for this situation, and riders can use the previous sections as a checklist of preparation tasks in order for an engine to deal with hot weather much better.

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