Video explanation
A cutaway shows piston, crank, valves and transmission, switching intake, compression, power and exhaust with slow motion to reveal timing.
Four strokes per cycle
Intake, compression, power and exhaust complete over two crankshaft revolutions.
Connecting-rod conversion
Gas pressure pushes the piston, and the rod and crank convert reciprocating motion into rotation.
Valve timing
Valves control gas exchange in relation to crank phase. Real engines can use different timing and ignition designs.