Which stroke in the four stroke cycle begin as the compressed fuel mixture is ignited in the combustion chamber?

The stroke that begins as the compressed fuel mixture is ignited in the combustion chamber is the power stroke. This occurs after the compression stroke when the spark plug ignites the fuel-air mixture, causing a rapid expansion of gases that pushes the piston down, generating power. This downward movement of the piston converts the chemical energy of the fuel into mechanical energy.