Two-stroke cycle

The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by having only two strokes (linear movements of the piston) instead of four, although the same four operations (intake, compression, power, exhaust) still occur. Thus, there is a power stroke per piston for every engine revolution, instead of every second revolution. Two stroke engines can be arranged to start and run in either direction.

Related Topics:
Internal combustion engine - Four-stroke cycle

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Two-stroke engines are used most among the smallest and largest reciprocating powerplants, but less commonly among medium sized ones.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The smallest gasoline engines are usually two-strokes. They are commonly used in outboard motors, high-performance, small-capacity motorcycles, mopeds, scooters, snowmobiles, karts, model airplane and motorized garden appliances like chainsaws and lawnmowers. In each application, they are popular because of their simple design (and consequent low cost) and very high power-to-weight ratios (because the engine has twice as many combustions per second as a four stroke engine revolving at the same speed). For handheld devices, they also have the advantage of working in any orientation, as there is no oil reservoir dependent upon gravity.

Related Topics:
Outboard motor - Motorcycle - Moped - Scooter - Snowmobile - Karts - Model airplane - Chainsaw - Lawnmower

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Two-stroke cycles have also been used in diesel engines, notably opposed piston designs, low speed units such as large marine engines, and V8 engines for trucks and heavy machinery.

Related Topics:
Diesel engine - Opposed piston - V8

~ ~ ~ ~ ~ ~ ~ ~ ~ ~