What is the oil-to-gasoline mixing ratio for a grass trimmer?

[DiHaley]

Greening grass trimmers are equipped with two-stroke gasoline engines, and the recommended gasoline-to-oil mixing ratio is either 25:1 or 30:1. Below are the relevant details: A two-stroke gasoline engine has three ports on the cylinder block—the intake port, exhaust port, and transfer port—which are closed by the piston at specific times. Its working cycle consists of two strokes: First stroke: The piston moves upward from the bottom dead center, and after all three ports are closed, the air-fuel mixture in the cylinder is compressed. When the intake port is exposed, the combustible mixture flows into the crankcase. Second stroke: As the piston nears the top dead center, the spark plug ignites the combustible mixture, and the expanding gases push the piston downward to perform work. During this time, the intake port remains closed, and the combustible mixture sealed in the crankcase is compressed. When the piston approaches the bottom dead center, the exhaust port opens, allowing the exhaust gases to escape. Subsequently, the transfer port opens, and the pre-compressed combustible mixture rushes into the cylinder, displacing the exhaust gases and completing the scavenging process.