COMPRESSION STROKE :

In this stroke the piston moves from BDC to TDC and both the valves are closed. The piston compresses the air-fuel mixture inside the cylinder. When the air-fuel mixture get compressed the temperature of the air-fuel mixture is increased. In this process the crankshaft rotates further 180 degrees. So the total amount of degrees is now 360 degrees.

Fig. Compression stroke

* Intake stroke

* Compression stroke

* Power stroke

* Exhaust stroke