Suzuki 2005 GSF1200 Service Manual page 168

1G-6 Fuel System:
Main System
As the throttle valve (1) is opened, engine speed rises and negative pressure in the venturi "A" increases. This causes
the piston valve (2) to move upward.
The fuel in the float chamber (3) is metered by the main jet (4). The metered fuel enters the needle jet (5), mixes with
the air admitted through the main air jet (6) and forms an emulsion.
The emulsified fuel then passes through the clearance between the needle jet (5) and jet needle (7) and is discharged
into the venturi "A", where it meets the main air stream being drawn by the engine.
Mixture proportioning is accomplished in the needle jet (5). The clearance through which the emulsified fuel must flow
ultimately depends on throttle position.
1
1. Throttle valve
2. Piston valve
3. Float chamber
2
7
"A"
6
5
3
4
4. Main jet
5. Needle jet
6. Main air jet
"B"
"C"
"D"
7. Jet needle "C": Fuel/Air mixture
"A": Venturi "D": Fuel
"B": Air
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