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DISASSEMBLY
Vacuum Piston Chamber
1.
See
Figure 4-14.
Remove screws (26, 25) and throttle
cable bracket (24).
2.
Remove three shouldered screws (2). Remove top cover
(1) and spring (3).
3.
Lift out vacuum piston (4) with jet needle (6) and spring
seat (5). Remove loose parts from vacuum piston.
Carburetor Body
1.
See
Figure 4-14.
Remove four screws and lockwashers
(18). Remove float bowl assembly (38).
2.
Remove pin (14), float (16) and fuel inlet valve (13).
3.
Back out main jet (11) and needle jet holder (10). Needle
jet (9) is free to be removed from bottom end of passage.
4.
Insert thin-bladed screwdriver into slow jet passage to
remove slow jet (12).
Accelerator Pump
1.
Remove three screws (49), lockwashers (48), accelerator
pump housing (42), spring (43) and diaphragm (44).
Remove O-ring (45) from housing.
CLEANING, INSPECTION AND
REPAIR
Vacuum Piston Components
1.
See
Figure 4-14.
Hold vacuum piston up to strong light.
Examine diaphragm at top of vacuum piston (4) for evi-
dence of pinching, holes or tears. Replace if damaged.
2.
Examine vacuum passage through bottom of piston (4).
Clean passage if restricted.
3.
Examine spring (3) for stretching, crimping, distortion or
damage. Replace if necessary.
4.
Examine slide on sides of piston (4) to be sure surface is
smooth and clean. Clean or buff out any rough surfaces.
5.
Examine jet needle (6) for evidence of bending or dam-
age. Needle should be straight; surface of taper should
be smooth and even.
6.
Check float bowl O-ring (53) for any distortion or dam-
age. Replace if seating surfaces are damaged.
7.
Examine fuel inlet valve (13) and inlet valve seat. Clean
with carburetor cleaner. Replace if seating surfaces are
damaged.
8.
Clean slow jet (12) with carburetor cleaner. Check to be
sure all orifices are open.
9.
Check enrichener valve (22). Be sure needle guide is
clean, straight and undamaged. Check composition seat-
ing surface for wear or damage. Replace if damaged.
10. Check enrichener valve chamber. Clean with carburetor
cleaner. Check that all passages are open and free of
obstruction.
11. Clean needle jet (9). Replace if damaged.
www.PlanDeGraissage.org
12. Clean all internal fuel/air passages and jets. Check that
all passages and jets are open and free of obstruction.
13. Check needle jet holder (10). Clean bleed tube orifices.
Replace holder if damaged.
14. Check float (16) for cracks or other leaks. Replace if
damaged.
15. Clean main jet (11) with carburetor cleaner and inspect
for damage. Replace if damaged.
Accelerator Pump
1.
See
Figure 4-14.
Inspect the accelerator pump dia-
phragm (44) for holes, cracks or deformation. Replace as
necessary.
2.
Replace the accelerator pump rod (51) if it is bent;
replace the boot (50) if cracked.
ASSEMBLY
Vacuum Piston Chamber
1.
See
Figure 4-14.
Place jet needle (6) through center hole
in vacuum piston (4). Place spring seat (5) over top of
needle.
2.
Insert vacuum piston (4) into carburetor body. The slides
on the piston are off-center and the piston will fit into the
slide track grooves one way only. If piston does not fit,
rotate 180 .
3.
Check to be sure diaphragm is seated evenly into groove
at top of carburetor body. Place spring (3) over spring
seat (5), and carefully lower top cover (1). Keep spring
straight while lowering top cover.
4.
After top cover (1) is seated, hold top cover while lifting
vacuum piston (4) upward. Piston should raise to top
smoothly. If piston movement is restricted, spring (3) is
cocked; lift up top cover, then lower carefully, keeping
spring coils straight.
5.
Once top cover is installed correctly, install three shoul-
dered screws (2). Place throttle cable bracket (24) in
position with idle screw (27), resting on top of throttle
cam stop. Install body screw and washer (26) first, then
top screw (25) to prevent bending bracket or throttle cam.
Carburetor Body
CAUTION
Slow jets from fixed-venturi carburetors look the same as
the slow jet of the C.V. carburetor. However, the air bleed
hole sizes are different on fixed-venturi carburetors and
they must not be installed on C.V. carburetors.
1.
See
Figure 4-14.
Thread slow jet (12) into slow jet pas-
sage with narrow-bladed screwdriver.
2.
Turn carburetor upside down. Place needle jet (9) in main
jet passage with needle passing through center hole. Be
sure end of jet with larger opening and chamfered sur-
face enters passage first.
4-15
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