Two-stroke engines, operation, seizure, lean mixture, chainsaw

The article presents a discussion on the possibility of damage to a two-stroke engine used in modern chainsaws. It outlines the design of engines applied to chainsaws, taking into account new design trends. Furthermore, it contains information regarding the causes of chainsaw engine damage, with particular emphasis on the possibility of piston seizure in the engine cylinder. It presents the results of tests on a seized engine and explains the causes of its failure. The theoretical and practical analysis of the phenomenon is concluded with findings.Low-power two-stroke gasoline engines are still used to build drive systems for machines and vehicles. Unlike four-stroke engines, they have different design features, primarily resulting from the use of a different type of timing, lubrication, and cooling systems.
In current applications, the two-stroke engine is most often designed as a high-speed unit, used, among others, in motorboat sports, mopeds, and small utility machines such as chainsaws, brushcutters, lawnmowers, etc. Of the groups mentioned, the use of the two-stroke engine is most widespread in machines used in agriculture, gardening, and forestry. Especially in handheld machines, as it has a high power-to-weight ratio (for chainsaws it is 1.5 – 3.5 kg/kW). In the article, it was decided to address the issue of two-stroke engines used in the aforementioned combustion chainsaws, due to the widespread use and, consequently, the failure rate of these devices. (…)

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