8.
Install adjusting needle with its spring. Turn
in
until main seats and back out
1
to 1-1/2 turns.
9.
Install idleadjusting
screw fingertight-Then
back
out
1
to
1-1/2
turns.
10.
Reinstall choke and adjust.
11.
Install air horn assembly and gasket.
12.
Install carburetor on engine and connect gas-
oline inlet, governor mechanism breather hose
and choke.
13. Install air cleaner and air housing top and door.
GASEOUS FUEL CARBURETOR
The gaseous fuel carburetor (Figure 25) is similar to
the gasoline carburetor
in
shape, but it differs
in
operation. The gaseous carburetor contains two
major sections, the idle circuit and the load circuit.
Fuel delivery depends on the demand created on the
fuel inlet line, Figure
26.
A small vacuum on the inlet
line opens the fuel regulator, delivering fuel. For no-
load operation, the idle adjustment controls the
quantity of fuel allowed through the idle port. The
throttle is almost closed,
so
the increased vacuum on
the engine side of the carburetor draws fuel through
the idle passage. When load increases, the flow of air
through the carburetor draws fuel from the main fuel
port located at the venturi of the carburetor..
Adjustment:
Set the carburetor idle adjustment and
then the load adjustment.
If
the carburetor
is
completely out
of
adjustment
so
the engine
won't run, open the idle adjustment one or
two
turns: then crank the
engine while opening the main adjustment, until the engine starts.
Adjust the carburetor in the same manner as the
gasoline carburetor. Usually the idle adjustment will
have little effect on operation, because
of
the high
engine speed.
Removal and Disassembly:
1.
Remove air housing door and top panel, fuel hose
2.
Remove two carburetor mounting nuts and pull
3. Remove float bowl (and main adjustment screw
5.
Remove throttle plate screws and plate and pull
and governor linkage.
off carburetor.
begin Spec
R).
Figure
26.
out throttle shaft.
Repair and Assembly:
Clean in a suitable carburetor
cleaner and blow out the idle passage. Check the idle
needle for
wear
or
damage and the main adjustment
for worn threads. For assembly, reverse the dis-
assembly procedure.
GAS
IDLE
ADJUSTMENT
PRIOR
TO
SPEC.
R
GAS
HOSE
TO
REGULATOR
GAS
MAIN
ADJUSTMENT
GAS IDLE
ADJUSTMENT
-1
-
HOSE TO
REGULATOR
1
BEGIN
SPEC
R
t
FIGURE
2s.
GASEOUS
FUEL'
CARBURET~R
PRIOR TO
SPEC.
R
-
BEGIN
SPEC.
R
-
3TTLE
FIGURE
26.
GASEOUS FUEL ADJUSTMENTS
25
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