Carburetors - Polaris TX Starfire Owner's Manual

CARBURETORS
The Mikuni carburetor has varying operations depending upon
varying driving conditions. It is constructed with the float
system, the pilot system, the main system, and the starter
system (initial starting device).
FLOAT SYSTEM
The float system is designed to maintain a constant height of
gasoline during operation.
When the fuel flowing from the fuel pump into the float cham-
ber through the needle valve reaches the constant fuel level, the
float rises. When the buoyancy of the float and the fuel pres-
sure of the fuel pump balance, the needle valve sticks fast to
the needle seat, preventing further delivery of gasoline, there-
by holding the standard level of gasoline.
The standard level of gasoline is set at below 30 m/m.± 1 from
the center of the main bore.
STARTER SYSTEM
The starter system is designed to make the engine start quickly
in cold weather. It is constructed with functional parts such as
a starter jet, a starter emulsion tube, and a starter plunger, etc.
When the engine starts with the throttle valve closed and the
starter plunger wide open, the intake negative pressure of the
engine works on the fuel nozzle. By this negative pressure, the
fuel is measured by the starter jet, mixed with air in the starter
emulsion tube, absorbed into the plunger chamber, mixed
again with air from the starter air inlet, made the most suitable
concentration of fuel-air mixture for initial starting, and deliver-
ed to the engine through the fuel nozzle.
In this starter system, you can be sure of initial starting without
any skill of operation, since both fuel and air are measured and
the constant fuel-air mixture ratio is always correct.
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