A 4-stroke engine refers to the type of internal combustion engine commonly used in motorcycles and other vehicles. It is named "4-stroke" because it completes four distinct phases or strokes to complete one combustion cycle. The four strokes are as follows:
Intake Stroke: The piston moves downward, creating a partial vacuum in the cylinder. This allows the intake valve to open, allowing a mixture of fuel and air to be drawn into the combustion chamber.
Compression Stroke: The piston moves upward, compressing the fuel-air mixture in the combustion chamber. Both the intake and exhaust valves remain closed during this stroke.
Power Stroke: Once the mixture is compressed, the spark plug ignites it, causing a controlled explosion. This explosion forces the piston downward, creating power that is transferred to the crankshaft, which drives the motorcycle's wheels.
Exhaust Stroke: As the piston moves upward again, the exhaust valve opens, allowing the burned gases resulting from the power stroke to be expelled from the combustion chamber and out through the exhaust system.
This four-stroke cycle is repeated continuously as the engine runs, allowing the motorcycle to generate power and propel itself forward. The 4-stroke design offers several advantages, including better fuel efficiency, smoother operation, and reduced emissions compared to 2-stroke engines.