https://www.wholetoolbox.com/makita-038-118-180-chainsaw-decompression-valve
The Makita 038-118-180 Chainsaw Decompression Valve is designed to make engine starting smoother and easier by reducing cylinder compression during ignition. This small yet essential component works by temporarily releasing built-up pressure in the combustion chamber, allowing the starter rope to pull with less resistance. Once the engine fires up, the valve automatically closes, enabling normal compression for efficient operation. By minimizing strain on both the user and the starter mechanism, it helps extend the lifespan of the chainsaw while ensuring consistent performance.