Answer for What is the second stroke in a Petrol Engine

The compressed mixture is ignited with a spark from the spark plug. The gases spread and pressure is exerted on the piston. In the second stroke, the piston moves from T.D.C. towards B.D.C. Thus the function of power stroke is carried out.. When the piston comes down, the exhaust port opens up and the exhaust gases are released. In this way, even the act of exhaust stroke is also performed. At this moment, the pressure of piston is exerted on the mixture in the crank case and the mixture to some extent, comes into the cylinder through the transfer port, after being compressed. In this way, the strokes occur turn by turn and the engine keeps on working