Answer for What is First Stroke in an Engine

In the first stroke, the piston moves from B.D.C. towards T.D.C. When the piston goes up, the inlet port is opened and the mixture of air and petrol comes into crank case through carburetor from its passage. Thus the suction activity is performed. In the same stroke, the piston compresses the mixture received in the cylinder and thus the activity of compression is also completed.