Carburetor Operation; Carburetor Removal/Installation - Yamaha V star 1100 Owner's Manual

AIR/FUEL, EXHAUST AND EMISSION CONTROL SYSTEMS
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CARBURETOR
Operation
The carburetor atomizes fuel and mixes it in cor-
rect proportions with air that is drawn in through the
air intake. At the primary throttle opening (idle), a
small amount of fuel is siphoned through the pilot
jet by the incoming air. When the throttle is opened
further, the air stream begins to siphon fuel through
the main jet and needle jet. As the tapered needle is
lifted, it occupies progressively less area within the
needle jet, which increases the effective flow capac-
ity of the jet. At full throttle, the carburetor venturi
is fully open and the needle is lifted far enough to
permit the main jet to flow at full capacity.
The choke circuit is a bystarter system. The choke
lever in this system opens a starter valve rather than
closing the butterfly in the venturi. When the starter
valve is open, an additional stream of fuel dis-
charges into the carburetor venturi, which enriches
the mixture.
Removal/Installation
NOTE
The carburetors have several hoses
connected to various fittings. During
removal, mark each hose and its fit
ting so the hoses can be installed on
the correct fittings during assembly.
Also note how each hose is routed
along the motorcycle. Hoses must be
rerouted along their original paths.
1. Securely support the motorcycle on a level sur-
face and disconnect the electrical lead from the neg-
ative battery terminal (Figure 2).
2. Remove the fuel tank as described in this chap-
ter.
3. Remove the air filter housing and the surge tank
as described in this chapter.
4. Loosen the clamp (A, Figure 23) and remove
the carburetor duct (B) from each carburetor.
5. On California models, disconnect the EVAP
purge hose (A, Figure 24) from the fitting on the
front of the front carburetor.
6. Pull the carburetor slide breather hose from the
holder (B, Figure 24) on the side of the front carbu-
retor, and disconnect the fuel line (C) from the front
carburetor fitting.
7. Remove the mounting screws and lower the car-
buretor cover (B, Figure 4) from its mounting
bracket.
8. Remove the AIS vacuum line (Figure 25) from
the fitting on the rear carburetor intake manifold.
9. Disconnect the fuel line (C, Figure 23) from the
rear carburetor fitting.
10. Note how the throttle and choke cables are
routed along the left side of the motorcycle. If neces-
sary, release the cables from the holder (B, Figure 7).
11. Loosen the pull cable locknut (A, Figure 26)
and the return cable locknut (B). Release each cable
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