Two-stroke engine
Internal combustion engine type / From Wikipedia, the free encyclopedia
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes of the piston (one up and one down movement) in one revolution of the crankshaft. A four-stroke engine requires four strokes of the piston to complete a power cycle in two crankshaft revolutions. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust (or scavenging) functions occurring at the same time.
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Two-stroke engines often have a high power-to-weight ratio, power being available in a narrow range of rotational speeds called the power band. Two-stroke engines have fewer moving parts than four-stroke engines, and thus are cheaper to manufacture. In countries and regions with stringent emissions regulation, two-stroke engines have been phased out in automotive and motorcycle uses. In regions where regulations are less stringent, small displacement two-stroke engines remain popular in mopeds and motorcycles.[1] They are also used in power tools such as chainsaws and leaf blowers.