What stroke follows the exhaust stroke in a 4-stroke engine cycle?

In a four-stroke engine cycle, the stroke that directly follows the exhaust stroke is the compression stroke. This sequence is key to the functioning of the engine.

During the exhaust stroke, the combustion gases are expelled from the cylinder, and once this stroke is complete, the piston moves back down to create a vacuum during the intake stroke. However, before any fresh fuel/air mixture enters the cylinder, it's necessary for the piston to move back up to compress the new mixture after it has been drawn in. This is the compression stroke.

During the compression stroke, the piston travels from the bottom of the cylinder back up to the top. The purpose of this stroke is to compress the air-fuel mixture in preparation for ignition, which occurs just after the compression is complete. This compression raises the pressure and temperature of the mixture, making it more efficient to ignite when the spark plug fires.

Understanding the sequence of these strokes is crucial for grasping how four-stroke engines operate and the timing involved in each phase of the cycle.