Buell S1 Lightning, Руководство по ремонту

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4-2
CARBURETOR
GENERAL
See Figure 4-1. Buell motorcycles use a constant-velocity,
gravity-fed carburetor. This carburetor features a float-oper-
ated inlet valve, a variable venturi, a throttle stop screw (for
idle speed adjustment) and a fuel enrichment system (for
starting).
Idle and transfer ports provide a balanced fuel mixture during
the transition period from stop to mid-range. A vacuum piston
controls venturi opening.
The carburetor is specifically designed to control exhaust
emissions. All jets are fixed. The idle mixture has been pre-
set at the factory. The idle mixture screw is recessed in the
carburetor casting. The opening is sealed with a plug
because it is intended that the idle mixture be non-adjustable.
NOTE
Adjusting mixture setting by procedures other than specified
in this section may be in violation of Federal or State regula-
tions.
This system partially compensates for changes in the mixture
that are normally caused by changes in altitude. Because
atmospheric pressures drop as altitude increases, the pres-
sure difference in the upper and lower chambers is reduced;
this results in less fuel being delivered to the engine, thereby
maintaining the correct air/fuel ratio for better engine perfor-
mance and reduced exhaust emissions.
The carburetor has a drain for emptying the float chamber
during seasonal or extended periods of storage.
The carburetor is equipped with an accelerator pump. The
accelerator pump system uses sudden throttle openings
(rapid accelerations) to quickly inject raw fuel into the carbu-
retor venturi; this provides extra fuel for smooth acceleration.
Figure 4-1. Carburetor
1. Vacuum piston chamber
2. Float chamber
3. Accelerator pump
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