The four-stroke petrol engine works in four stroke.
That is why it is called four-stroke petrol engine.
The four strokes are called:
A*inlet stroke
B*compression stroke
C*power stroke
D*exhausting stroke
During the inlet stroke, the inlet valve is opened
by a calm of the turning camshaft and
the petrol-air mixture passes the fuel injection unit
into the combustion chamber.The piston goes down.
During the compression chamber is closed and the
petrol-air mixture is compressed in the compression chamber.
The mixture is ignited by a spark that is produced
by the spark plug.
During the power stroke the ignited petrol-air mixture explodes
and converts into hot gases. The expansion of the gases pushes
the piston down agein and transmits energy to the wheels
over the crankshaft and power transmission shaft.
During the exhausting stroke the outlet valve is open,
the piston goes up gain and the gases passes the combustion chamber
over theexhaust valve into the exhausting system