1, the intake stroke, the engine began to work, the first into the “intake stroke”,     the cylinder head intake valve open, the exhaust door closed, the piston from the upper dead point down to the lower dead point, the volume of the cylinder gradually increased, the air pressure is lower than the outside atmospheric pressure. So the fresh gasoline and air mixture, through the open intake valve is sucked into the cylinder；

2, compression stroke, after the intake stroke, the second stroke, that is, the “compression stroke”. At this time, the crankshaft by inertia continues to rotate the piston from the lower dead center upward push. At this time, the intake door is closed as tightly as the exhaust door. Cylinder volume gradually reduced, and the gas mixture by the piston’s strong compression. When the piston moves to the upper dead point, the gas mixture is compressed in the upper dead point and the cylinder head between the small space;.

3, work stroke, after the compression stroke is “work stroke”, is also the third stroke. In the compression stroke is almost over, the piston is close to the dead point, the cylinder head of the spark plug through the high-voltage electrical generation of electric sparks, the gas mixture will be ignited, the combustion time is very short, but the speed is very fast. The gas expands violently and the pressure increases sharply. The piston under the strong pressure of the gas, down to the dead point of rapid movement, pushing the connecting rod also run under the door, the connecting rod will drive the crankshaft to turn up;