A 4-stroke motorcycle engine, also known as an internal combustion engine, follows a specific cycle of operations to convert fuel into mechanical energy. Here's a simplified explanation of how a 4-stroke motorcycle engine works:
Intake Stroke: The piston moves downward, creating a partial vacuum within the cylinder. The intake valve opens, allowing a mixture of air and fuel to enter the combustion chamber from the intake manifold. The piston remains at the bottom of the cylinder during this stroke.
Compression Stroke: The intake valve closes, and the piston moves upward, compressing the air-fuel mixture within the cylinder. This compression raises the temperature and pressure of the mixture.
Power Stroke: Once the piston reaches the top of its compression stroke (top dead center), a spark plug ignites the compressed air-fuel mixture. The resulting explosion rapidly increases the pressure within the cylinder, driving the piston downward with considerable force. This downward motion is transmitted to the crankshaft through a connecting rod, converting it into rotational motion and generating power.
Exhaust Stroke: After the power stroke, the piston moves upward again, but this time, the exhaust valve opens. As the piston moves up, it pushes the remaining combustion gases out of the cylinder and into the exhaust system. The exhaust valve then closes, completing the exhaust stroke.
This 4-stroke cycle repeats continuously as the engine runs, with each stroke occurring in a specific order: intake, compression, power, and exhaust. The engine's crankshaft is connected to the transmission, which transfers the rotational motion to the wheels, propelling the motorcycle forward.
The engine's camshaft, driven by the crankshaft, operates the intake and exhaust valves. The camshaft's lobes open and close the valves at precise intervals, synchronized with the piston's position, to control the intake and exhaust processes.
The combustion process in a 4-stroke engine is often smoother and more efficient compared to 2-stroke engines, as it separates the intake and exhaust processes and allows for better control of fuel-air mixture, resulting in improved fuel economy and reduced emissions.