kaksitahtoiset

Kaksitahtoiset refers to two-stroke engines, a type of internal combustion engine distinguished by its power cycle completed in two piston strokes and one crankshaft revolution. This contrasts with four-stroke engines, which require four strokes. The two-stroke cycle typically involves intake and compression occurring simultaneously during the upward stroke, followed by combustion and exhaust during the downward stroke. This design is generally simpler and lighter than four-stroke engines, often resulting in a higher power-to-weight ratio.

The operation of a two-stroke engine involves the piston moving upwards, compressing the fuel-air mixture in the cylinder while simultaneously drawing a fresh charge into the crankcase through an intake port. As the piston reaches the top, the spark plug ignites the compressed mixture, driving the piston downwards. During this downward movement, the piston uncovers an exhaust port, allowing burnt gases to escape, and then an intake or transfer port, admitting the fresh fuel-air mixture from the crankcase into the cylinder. This continuous process makes them efficient for their size.

Two-stroke engines are commonly found in applications where simplicity, low weight, and high power output are advantageous. Examples include motorcycles, mopeds, outboard motors for boats, chainsaws, leaf blowers, and some smaller aircraft. However, they are known for producing more pollution and consuming more oil than comparable four-stroke engines due to the oil being mixed with the fuel for lubrication and burnt during combustion. Emission regulations have led to a decline in their use in many mainstream applications, with cleaner four-stroke alternatives becoming more prevalent.