On motorcycles, the most common engines are attributed to piston reciprocating internal combustion engines. The four - stroke engine and the two - stroke engine are commonly known as this type of engine, with cylindrical pistons moving up and down inside. There are many classifications for engines, for example, three classifications.
Classification by travel
The engine can be divided into two strokes and four strokes according to the stroke. Now, the domestic four stroke engines are widely used. Here we have a repeat of four stroke.
The four flush engine means that the piston does four times of reciprocating cylinder point fire. Namely：
1. intake: at the moment the inlet valve opens, the piston goes down, and the mixture of gasoline and air is sucked into the cylinder.
2. contraction: at the moment the intake door and the exhaust door are closed together, the piston goes up, and the mixture is tightened.
3. incineration: when the mixer is tightened to the hourly spark plug, the blinding fire points with the mixing gas, the pressure produced by the incineration push the piston down and the crank shaft rotates.
4. exhaust: when the piston goes down to the lowest point, the exhaust valve opens, the exhaust gas is discharged, and the piston goes up continuously to discharge the remaining waste gas.
The 4 trips are carried out individually, so the operation is high in power and good in stability. The speed range of low speed to high speed is large
Reduction of gas flow loss and low fuel consumption.
Low speed work smooth, smooth and smooth, not easy to overheat.
Volume power, uniform and useful pressure.
The heat load is smaller than the two stroke engine. Large capacity, can be planned as a high power engine.
The valve distribution mechanism is complicated, the parts are many, the maintenance is difficult
Large mechanical noise
Because the 2 rotation of the crankshaft is 1 times, so the rotation balance is unstable