A single-cylinder engine is a piston engine with one cylinder. They are often used for motorcycles, motor scooters.Most single-cylinder engines used in motor vehicles are fueled by petrol and use a four-stroke cycle.
source/image(PrtSc): Lubrizol Additives 360
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction.
A 4-stroke motorcycle has a more compact and complex design that relies on the same oil to lubricate the engine, clutch and gearbox. A single-cylinder Four Stroke gasoline engine completes a working cycle through four strokes of intake, compression, work, and exhaust.
The first stroke is intake,,valve opens crankshaft rotates 1/2 turn pulling the piston down the bore drawing in fuel and air.Second comes compression whereby the valve closes and the crank turns another half turn bringing the piston up to compress the mixture.Third comes the power stroke,where the spark plug lights off this mixture,raising cylinder pressure tremendously,forcing the piston down the bore.Fourth and last the exhaust valve opens and the crank turns it”s final half turn expelling the exhaust gas.via/quora/Greg Mahoney