FUEL SYSTEM
Throttle Opening vs. Fuel Flow
In a full throttle condition the cross sectioned area between the
jet needle and the needle jet is larger than the cross sectioned
area of the main jet. The main jet therefore has greater control
over fuel flow.
Main Jet
When the throttle opening becomes greater and the area
between the needle jet and jet needle increases, fuel flow is
metered by the main jet. The number on the jet indicates the
amount of fuel
CCs which will pass through it in one minute under controlled
conditions. Larger numbers give a greater flow, resulting in a
richer mixture.
Throttle slide
The throttle slide controls the rate of engine air intake by
moving up and down inside the main bore. At small throttle
openings, air flow control is performed chiefly by the cutaway.
By controlling air flow the negative pressure over the needle
jet is regulated, in turn varying the fuel flow.
Throttle valves are numbered 1.0, 1.5, 2.0, etc., according to
the size of the cutaway. The higher the number, the leaner the
gasoline/air mixture.
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