Kaksitahtinen

Kaksitahtinen refers to a two-stroke internal combustion engine. This type of engine completes a power cycle with two strokes of the piston, corresponding to one crankshaft revolution. Unlike four-stroke engines, two-stroke engines typically have intake and exhaust ports instead of valves. Combustion happens on every revolution, leading to a higher power-to-weight ratio compared to four-stroke engines of similar displacement.

The operating principle involves the piston moving down, compressing the fuel-air mixture in the crankcase. As the piston moves up, it creates a vacuum in the crankcase, drawing in a fresh fuel-air mixture. Simultaneously, the piston uncovers the exhaust port, allowing burnt gases to escape, and then the intake port, allowing the compressed mixture from the crankcase to enter the cylinder for combustion.

Two-stroke engines are known for their simplicity, fewer moving parts, and lighter weight. This makes them suitable for applications where these characteristics are advantageous, such as in small motorcycles, chainsaws, leaf blowers, and some outboard motors. However, they often suffer from less efficient fuel combustion, leading to higher emissions of unburnt hydrocarbons and a tendency to consume oil mixed with the fuel for lubrication.