General Theory; Diaphragm And Piston Operation - PGO G-MAX 50 Service Manual

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General theory

DIAPHRAGM AND PISTON OPERATION

The carburetor is a variable-venturi type, whose venturi cross sectional area is increased or
decreased automatically by the piston valve . The piston valve moves according to the negative
pressure present on the downstream side of the venturi A. Negative pressure is admitted into the
diaphragm chamber
Rising negative pressure overcomes the spring
diaphragm chamber and prevent the air velocity from increasing. Thus, air velocity in the venturi
passage is kept relatively constant for improved fuel atomization and precise air/fuel mixture.
through an orifice provided in the piston valve .
force, causing the piston valve to rise into the