How does a cylinder from a petrol engine work?

The heart of an engine

The cylinders are the main part of an internal-combustion engine. For less emissions and fuel consumption car brands produce cars with only 3 or 2 cylinders and a smaller cylinder capacity. Cars with only 2 cylinders are quite bad in acceleration and have an inconstant, unrhythmical sound. But some motorcycles have those types of engines because they have less weight and enough power for a two-wheel motorbike.

Cylinder by cylinder

A cylinder with four strokes has an admission valve where the mixture of oxygen and fuel gets injected in the cylinder. As the piston rises, the poppet valve is forced shut by the increased cylinder pressure. Flywheel momentum drives the piston upward, compressing the fuel/air mixture. The sparkplug ignites the compressed fuel, at the top of compression stroke. As the fuel burns it expands, driving the piston downward. Now the connecting rod turns around and the crankshaft starts to circle. While it´s circling, opens the popped valve and draws the emissions out of the cylinder. The camshaft controls the vents and closings of the admission/ popped valve. So, after that the whole cycle starts again.