Water cooling is a cooling method with good heat dissipation effect. The principle of water cooling is to cool the cylinder liner and cylinder head by wrapping the flowing water. Its cooling system will contain coolant, which will circulate small and large at the current engine temperature under the drive of the water pump. This benefit will make the engine temperature relatively balanced, without excessive performance. The throttle valve of the water-cooled vehicle will not open when the temperature is low; When the oil temperature is high, the throttle valve will be fully opened, and the water tank will start to work. When the temperature is too high, the fan will be opened to cool down to the optimal operating temperature of the engine. It is suitable for motorcycles with large displacement and large power. The heat generated by motorcycles with small displacement can not be cooled by water.

Basic accessories of water cooling: water pump, water tank temperature control and fan.

Disadvantages of water cooling: high cost, complex structure, high failure rate, because the space occupied by external water tank is also large. The blind change of water cooling not only does not improve the performance, but will make the hot car time longer, the cold car wear too much, and burn the engine oil in advance.

Oil cooling is to use the engine’s own lubrication system to dissipate heat through the oil radiator. No additional liquid is required, and the working process is relatively simple. The oil radiator and water tank are basically the same principle, but one is oil and the other is water.

Basic accessories of oil cooling: low-end oil cooling only needs an oil radiator, while high-end oil cooling will be equipped with fans and throttle valves.

Advantages of oil cooling: obvious heat dissipation effect, low failure rate, low oil temperature can reduce the high viscosity of oil.

Disadvantages of oil cooling: it only cools the temperature of the engine oil, not the cylinder block and cylinder head, so the heat dissipation effect is average. There are restrictions on the engine oil quantity. The radiator cannot be too large. If it is too large, the oil will flow into the oil radiator, causing insufficient lubrication at the bottom of the engine.

Changing from air cooling to oil cooling must match the pressure of radiator and oil pump. Too large oil radiator capacity is bad for engine gear lubrication, too small radiator flow is too small, which will have pressure on the oil pump, and insufficient oil flow will cause great wear on the cylinder head. However, some oil cooled models also have high performance. This type of engine will adopt a dual oil circuit design, and the cylinder block will be designed as a hollow state, which will allow the heat dissipation oil circuit to directly cool the cylinder block, so that its heat dissipation effect will be more efficient.

Air cooling refers to cooling by the wind brought by the vehicle. Large heat sinks will be designed on the surface of the engine cylinder block, and heat sinks and air ducts will be designed on the cylinder head to increase the contact area between the engine and air.

Advantages of air cooling: zero failure of cooling system (natural cooling), low cost of air cooling engine and less space.

Disadvantages of air cooling: heat dissipation is slow and limited by the engine type. For example, air cooling is rarely used for in-line four cylinders, and the middle two cylinders cannot effectively dissipate heat. Therefore, most air-cooled engines will appear on single cylinder engines or V-shaped double cylinder engines that emphasize low torque output. An air-cooled engine with no defect in design has no problem when travelling long distances. It is not said that air-cooled engine is not suitable for long-distance travel. Harley V-shaped double cylinder air-cooled engine rarely fails due to excessive engine temperature.

Water cooling is an essential cooling system for multi cylinder high power and high speed engines (as well as water oil dual cooling). Small displacement 125 single cylinder vehicles are not suitable for water cooling. Generally, 125 displacement does not generate so much heat. Oil cooling is the standard configuration of mid end street cars, which pursues stability and fan heating effect. Single cylinder air-cooled cars are more suitable for changing to oil cooling, and the change from single cylinder air-cooled cars to oil cooling only requires adding an oil fan heater in the middle of the oil duct. Air cooling is the standard configuration of daily scooters. The zero failure engine cost of the cooling system is low. As long as it is properly maintained, the problem of high temperature will not occur, but the high temperature of water-cooled vehicles will be more frequent. In short, single cylinder low speed vehicle air cooling is the best choice.