This stroke begins at B.D.C, and ends at T.D.C. In this stroke the Piston compresses the air-fuel mixture. Both the Intake and exhaust valves are closed during this Stage.
This stroke begins at (T.D.C) and Ends at (B.D.C) . In T.D.C a spark ignites The air-fuel mixture and forces the piston to B.D.C. Producing mechanical work. Both valves still closed
the piston, once again, Returns from B.D.C. To T.D.C. While the exhaust valve Is open. This action expels the spent air-fuel mixture Through the exhaust valve. Spark plug, intake valve , exhaust valve , combustion chamber,piston,cranckshaft,crankcase