The engine that completes one work cycle in two strokes. The 42cc 2 stroke engine crankshaft turns one turn, and the engine works on the outside once. When the piston is compressed near the upper stop, the spark plug ignites the combustible mixture, and the gas expansion pushes the piston down to work. At this time, the intake hole is closed, the combustible mixture confined to the crankcase is compressed, the vent opens when the piston is near the bottom stop, the exhaust gas is flushed out, and then the ventilation hole is opened, the pre-pressured combustible mixture rushes into the cylinder to remove the exhaust gas and carry out the ventilation process.
The 42cc 2 stroke engine produces so much pollution that you may not see the pollution around us. Pollution comes from two sources: The first is the combustion of lubricants. To some extent, the lubricant fills all the two-stroke engines with smoke, and a heavily worn two-stroke engine releases large clumps of oily smoke. The second reason is not obvious. Whenever a large amount of new air/fuel is injected into the combustion chamber, some of them leak out of the exhaust vents. That's why you can see shiny lubricants around any two-stroke motorboat. Hydrocarbons released from new fuels mixed with leaked lubricants pose a major problem for the environment.