272144 Vanguard Twin Cylinder OHV BRIGGS & STRATTON.pdf

Check Throttle, Choke Shaft and Body For Wear
NOTE: The measurement in Step 1 is taken with the
carburetor off of the intake manifold.
1. Lay carburetor on 1/8” (3 mm) raised flat
surface (1). Use a feeler gauge (2) to check
throttle and choke shaft clearance as shown in
Fig. 96.
Throttle shaft and choke shaft clearance must not
exceed 0.010” (0.25 mm).
Fig. 94
Mikuni Carburetor
Models 290400, 303400, 350400 (Before
950801xx)
Carburetor Identification
Two carburetor bodies are used, depending upon
the use of a fuel pump (illustration A) or gravity feed
(illustration B) fuel delivery system, Fig. 95.
Besides a change in jetting, the end of the discharge
nozzle is machined at a different angle. Since the
discharge nozzle is an integral part of the carburetor
body the carburetor bodies are not interchangeable.
The carburetor bodies can be identified by looking
down the carburetor throat and comparing the end of
the discharge nozzle (1) in relation to the choke shaft
(2), Fig. 95. On a fuel pump carburetor the end of the
nozzle is at approximately a 20° angle (3) to the choke
shaft (2). On a gravity feed carburetor the end of the
nozzle is approximately parallel (4) to the choke shaft.
The fixed main jet used with a fuel pump system is
numbered 110. The fixed main jet used with a gravity
system is numbered 117.5.
A
Fig. 96
Ò
ÒÒ
ÒÒÒ
ÒÒ ÒÒ
ÒÒ
NOTE: The inspection in Step 2 is performed after
the carburetor has been disassembled.
2. Inspect throttle shaft and choke shaft for wear
(3), Fig. 97. Replace if worn.
B
Fig. 97
Replace either shaft if worn.
Replace the carburetor if the body is worn or if the
clearance on either shaft exceeds 0.010” (0.25 mm)
when a new shaft is used.
Fig. 95
Disassemble
1. Remove pilot jet (1), Fig. 98.
2. Remove four screws (2) and upper body (3).
Discard gasket (4).
99