Small engine

A small engine is the general term for a wide range of small-displacement, low-powered internal combustion engines used to power lawn mowers, generators, concrete mixers and many other machines that require independent power sources.

The smallest of all are used in handheld garden machinery, such as string trimmers and chainsaws, which have a displacement as small as 24 cc (1.5 cu in).

The combustion cycle can be either two-stroke (which results in a lighter engine for a given power output)[3][4] or four-stroke (which produce lower levels of exhaust gas emissions).

Rather than directly controlling the opening of the carburetor throttle, this is usually achieved by adjusting the governor, which in turn regulates the engine speed higher or lower.

[citation needed] Some engines in recent years, for example the Honda GC series, now use an overhead cam configuration.

The four largest manufacturers of small engines for power equipment in 2019 were Briggs & Stratton, Honda, Kawasaki and Kohler.

[18] In response to this, some jurisdictions, notably the US state of California, have imposed increasingly strict emissions regulations for small engines.

[19] The major alternative to small engines is the use of electric motors powered by rechargeable batteries.