Instead of trying to make an air-tight piston ... the pin pushes open a ball which acts as the inlet valve to pressurize an intermediate chamber. As the piston retracts, the ball closes the ...

The valve consists of two chambers separated by a piston and a spring. The crankcase pressure is drawn from the crankcase via ...

the choke valve, operated manually or automatically, closes the carburetor's air intake to maximize the fuel content of the air-fuel mixture delivered to the combustion chamber inside the engine.