"
CARBURETOR OVERHAUL
Carburetion problems that are not corrected by mixture
or float adjustments are usually a result
of
gummed-up
fuel passages or worn internal parts. The most effective
solution is a carburetor overhaul.
In general, overhauling a carburetor consists of dis-
assembly, a thorough cleaning, and replacement of
worn parts. Carburetor repair kits are available that
supply new gaskets and replacements for those parts
most subject to wear.
General instructions for overhauling a carburetor are
given below. Carefully note the position of all parts while
removing to assure correct placement when reassemb-
ling. Read through all the instructions before beginning
for a better understanding of the procedures involved.
Carburetor components are shown in Figures
14,
15
and
16.
Ignition
of
fuel can cause serious
laWAR"Gl
personal injury
or
death
6y
fire or
explosion.
Do
not permit any flame, cigarefte,
or
other
igniter near the fuel system.
Removal and Disassembly (Except Nikki)
1.
2.
3.
4.
5.
6.
7.
Disconnect all lines, linkages, wires, and attaching
nuts or bolts; then remove the carburetor from the
engine. (Downdraft carburetors may require removal
of the intake manifold to disconnect.)
Remove air cleaner adapter, if
so
equipped, and
automatic choking assembly.
Remove throttle and choke plate retaining screws,
then plates. Pull out throttle and chokeshafts, being
careful not to damage the teflon coating applied to
some throttle shafts.
Remove main and idle mixture screw assemblies.
On downdraftcarburetors, remove attaching screws
and separate upper and lower carburetor sections.
On sidedraft models, unscrew the retaining screw
and remove fuel bowl from the upper carburetor
body.
Carefully note position of float assembly parts then
slideout retaining pin and remove the float assembly,
any springs or clips, and the needle valve.
Unscrew and remove needle valve seat.
Removal and Disassembly (Nikki)
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 capscrews and lift
complete manifold assembly from engine. Remove
carburetor from intake manifold.
4.
Remove main jet and idle adjustment needle.
5.
Remove attaching screws and separate upper and
lower carburetor sections.
6.
Carefully note position of float assembly parts, then
7.
Remove needle valve.
pull out retaining pin and float assembly.
Cleaning and Repair
1.
Soak all metal components not replaced in carbu-
retor 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 objectsfor cleaning which
may increase the size of critical passages.
4.
Check the condition of the 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 (Except Nikki)
1.
Install needle valve and seat, fuel bowl gasket, and
float assembly. Make sure that all clips and springs
are properly placed and that the float moves freely
without binding. Check float level and adjust as
necessary.
2.
Rejoin upper and lower carburetor sections on
downdraft carburetors
-
fuel bowl and upper
carburetor body on sidedraft models.
The float spring on Zenith sidedraft carburetors
rides on the inner face of the fuel bowl. Be sure to
catch the end of the spring when reinstalling the
bowl (Figure
15).
3.
Slide in throttle shaft and install throttle plate, using
new screws if furnished
in
repair kit Before tight-
ening 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 small screwdriver,
then tighten screws. Install the choke shaft and plate
in the same manner.
4.
install main and idle mixture screw assemblies.
Turn in screws until lightly seated and then out the
number of turns specified in Table
1.
ACAUT~ON
Forcing the mixture adjusfmenf
screws tigbt will damage the
needle andseat. Turn
in
only
unfilligbt tension can
be felt.
5.
Reinstall carburetor on engine and connect fuel
lines, linkages, and wires.
6.
Reset mixture screws according to directions given
earlier in this section. Install air cleaner adapter,
where used, and air cleaner.
17
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