During which stroke is the air/fuel mixture ignited?

The air/fuel mixture is ignited during the power stroke of a four-stroke engine cycle. This is the stroke where the piston is at the top of its travel after the compression of the air/fuel mixture, which has been compressed to its optimal pressure and temperature. At this point, the spark plug creates a spark that ignites the mixture, causing a rapid expansion of gases. This expansion pushes the piston down, generating the power that ultimately drives the engine.

In contrast, the intake stroke is when air and fuel are drawn into the cylinder, and the compression stroke follows, where that mixture is compressed before ignition occurs. The exhaust stroke then expels the burnt gases from the cylinder. Understanding the sequences of these strokes is crucial for grasping how an internal combustion engine functions effectively.