FUEL AND CARBURETOR
6-13
FUEL DELIVERY
The throttle opening chart below demonstrates component
relationship to fuel flow versus throttle valve opening.
The pilot system’s main function is that of a low speed jet. Its
most effective range of fuel delivery is from idle to
approximately 3/8-throttle valve opening.
The throttle slide controls the rate of engine air by its
movement up and down in the carburetor venturi. At small
throttle openings the airflow is regulated chiefly by the valve
cutaway, with greatest effectiveness at 1/4 throttle opening.
Throttle valves are numbered 1.0, 1.5, 2.0, etc., according to
the size of the cutaway.
Decreasing the cutaway number will increase the amount of
fuel delivered in its effective range.
The jet needle and needle jet have an effective operating range
from approximately 1/8 to 7/8 throttle opening. The amount of
fuel delivered during this range relies upon the jet needle clip
position, as well as the needle jet size and other specifications.
The main jet affects fuel delivery at 1/4 throttle and
consistently increases to full throttle opening.
VENT SYSTEM
The fuel tank vent supplies atmospheric pressure to the fuel in
the tank. The vent must be free of debris and restrictions to
prevent lean mixture and possible engine damage. All vent
lines must be properly routed
Protect eyes from contact with cleaner. Take
appropriate safety measures during these
procedures. Safety glasses and chemical resistant
gloves are required. Should you get cleaner in your
eyes or if you swallow cleaner, seek medical
attention immediately.
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