Removal
1.
Remove air cleaner and hose.
2.
Disconnect governor and throttle linkage, choke
control and fuel line from carburetor.
3.
Remove the four intake manifold cap screwsand lift
complete manifold assembly from engine.
4.
Remove carburetor from intake manifold.
Disassembly (Walbro and Nikki)
1.
2.
3.
4.
5.
Remove throttle and choke plate retaining screws,
then plates.
Pull
out throttle and choke shafts.
Remove main jet and idle adjustment needle.
Remove attaching screws and separate upper and
lower carburetor sections.
Carefully note position of float assembly parts, then
pull out retaining pin and float assembly.
Remove needle and unscrew needle valve seat.
Disassembly (Nikki limited idle mixture)
1.
Remove main jet and idle adjustment needle.
2.
Remove attaching screws and separate upper and
3.
Carefully note position of float assembly parts, then
4.
Remove needle valve.
lower carburetor sections.
pull out retaining pin and float assembly.
Cleaning and Repair
1.
Soak all metal components not replaced in car-
buretor cleaner. Do not soak non-metal floats or
other non-metal parts. Follow the cleaning
manufacturer’s recommendations.
2.
Clean all carbon from the carburetor bore, especially
where the throttle and choke plates seat. Be careful
not
to
plug the idle or main fuel ports.
3.
Dry out all passages with low pressure air
(35
PSI).
Avoid using wire or other objects for cleaning that
may increase the size of critical passages.
4.
Check the condition of adjustment needle. Replace
if damaged. Replace float
if
loaded with fuel or
damaged.
5.
Check the choke and throttle shafts for excessive
play in their bore. This condition may necessitate
replacement of the carburetor.
6.
Replace
old
components with new parts.
Reassembly and Installation (Walbro and Nikki)
1.
Install needle valve and seat, main jet and float
assembly. Make sure that float pivot pin is properly
placed and that the float moves freely without
binding.
2.
Gently push float tang down until needle
just
seats;
measure float level as shown in Figure
4.
Adjust
float level if necessary. Release float tang and
measure float drop as shown in Figure
4
(the
distance from top of carburetor body to top of float).
3.
Position gasket on lower carburetor section and
install upper carburetor section.
4.
Slide in throttle shaft and install plate using new
screws. Before tightening the screws, the plate must
be centered in the bore.
To
do
so,
back
off
the
throttle stop screw as necessary and completely
close the throttle lever. Seat the plate by tapping
with a small screwdriver, then tighten screws. Install
the choke shaft and plate in the same manner.
5.
Install idle adjustment screw, throttle stop screw,
and fixed main jet plug or optional main fuel
adjustment needle.
6.
Mount carburetor on intake manifold and install
assembly on engine.
7.
Mount air cleaner assembly. Connect air intake
hose, breather hose, fuel line, vacuum line, and
throttle linkage.
8.
Adjust carburetor and governor according to
directions given in this section.
,I
Reassembly and Installation (Nikki limited idle
mixture)
1.
Install needle valve, main jet, and float assembly.
Make sure float pivot pin is properly placed and float
moves freely without binding.
2.
Turn carburetor on its side and measure float level
(Figure
4).
Adjust float level only if necessary.
Measure float drop (the distance from the top of
carburetor body to top of float). Adjust only if
necessary.
3.
Position gasket on lower carburetor section and
install upper carburetor section.
4.
Install idle adjustment screw, throttle stop screw,
and fixed main jet plug.
5.
Mount carburetor on intake manifold and install
assembly on engine.
6.
Mount air cleaner assembly. Connect air intake
hose, breather hose, fuel line, vacuum line, and
throttle linkage.
7.
Adjust carburetor and governor according to direc-
tions given in this section.
1
7-4
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