What is the first step in the operation of a four-stroke engine?

In a four-stroke engine, the first step in the cycle is the intake stroke, where fresh air (or a mixture of air and fuel) enters the combustion chamber. During this stroke, the intake valve opens, and the piston moves down, creating a vacuum that pulls the air/fuel mixture into the cylinder.

The process begins when the piston starts at the top of the cylinder, and as it descends, the fresh air or air-fuel mixture is drawn in. This is critical for the engine's operation, as having the right amount of fuel and air is essential for creating the optimal combustion conditions later in the cycle.

While ignition, compression, and exhaust are important steps in the four-stroke cycle, they occur after the intake phase. Having a solid understanding of the sequence of events in a four-stroke engine is crucial for comprehending how these engines operate effectively.