Onan NHC Series Operator's/Service Manual And Parts Catalog page 286

3. Set the idle adjustment screw for even operation
(so the engine is firing on both cylinders and is
running smoothly).
4. Release the governor mechanism to allow the
engine to accelerate. If the engine accelerates
evenly and without a lag, the main adjustment is
correct. If not, adjust the needle outward about
1/4 turn and again slow down the engine and
release the mechanism. Continueuntil theengine
accelerates evenly and without a time lag after
releasing the governor.
5. With the carburetor and governor adjusted, set
the throttle stop screw at the desired idle speed.
Float-Level Check: If the carburetor adjustment fails
to provide satisfactory operation, remove the car-
buretor and check the float level as follows:
1. Remove the fuel line, air cleaner hose, governor
linkage and choke wires.
2. Remove the two carburetor mounting nuts and
remove the carburetor.
3. Unscrew the float bowl nut and remove the entire
main fuel adjustment assembly from the float
bowl.
4. Invert the carburetor and check that the float
surface nearest the gasket is 1/8 ± 1/16-inch from
the gasket. Bend the float tab as required to
produce this spacing.
If the carburetor utilizes an intemally spring loaded fuel inlet
valve, the float surface should be 1/8 t 1/16-inch Irom the
gasket with the full weight of the float compressing the spring
in the needle.
5. Reassemble, install and test.
6. See Figure 15.
B E N D T A B
S T
G A S K E T T O F L O A T
D I M E N S I O N 1/8 I N C H
FIGURE 15. FLOAT LEVEL ADJUSTMENT
Carburetor Removal and Disassembly: Remove and
disassemble the carburetor assembly as follows,
referring to Figure 15:
1. Remove the fuel line, air cleaner hose, governor
linkage, and choke wires.
2. Remove the two carburetor mounting nuts and
remove the carburetor.
3. Remove the main jet assembly and bowl.
4. Remove the float pin and float.
5. Lift out the fuel inlet valve and unscrew the valve
seat.
6. Remove the idle adjustment needle.
7. Remove the throttle plate screws and thq plate,
then pull out the throttle shaft.
8. Remove the choke plate screws and plate, then
pull out the choke shaft.
Carburetor Assembly and Installation: Clean the
components and repair or replace defective or worn
parts. Use acetone or alcohol to dissolve gum
deposits if carburetor cleaner is not effective. Soak
the parts in carburetor cleaner, using it asdirected by
the manufacturer. Clean all carbon from the car-
buretor bowl, especially in the area of the throttle
plate. Blow out clogged passages with compressed
air. Check the needles, nozzle, and float for damage
or fuel loading. Check the choke and throttle shafts.
Reassemble and install as follows:
1. Install the throttle shaft and plate, using new
screws and lock washers. Install with bevel mated
to the carburetor body. If the plate is marked with
the letter C, install it with the mark on the side
toward the idle port when viewed from the flange
end of the carburetor. To centerthe plate, back off
the top screw, close the throttle leverand then set
the plate by tapping it with a small'screwdriver.
2. Install the choke shaft and plate. Centerthe plate
in the same manner as the throttle plate (see step
1'). Use new screws and lock washers,
3. Install the fuel inlet valve seat and. valve.
4. Install the float and floatpin, adjusting thefloatas
previously described.
5. Install the bowl ring gasket, bowl and bowl nut.
Make sure that the bowl is centered in the gasket
and tighten the main jet assembly securely. Turn
in until it seats and back out to 1-1/2 turns.
6. Install the idle adjusting screw finger-tight. Then
back it out 1 to 1-1/2 turns.
7. Install thechokeand adjustaspreviouslydescrib-
ed.
8. Install the carburetor on the engine and connect
the gasoline inlet, governor mechanism, air
cleaner hose, and choke wires.
9. Adjust the carburetor needle settings as describ-
ed under Adjustments and check out the perfor-
mance.
Complete Replacement: Complete replacement of
the carburetor should be performed as follows:
1. Follow the previously given disassembly instruc-
tions as required for removal of the defective
carburetor.
2. Replace the carburetor with a new unit, using
attaching parts in good condition and making all
the connections previously disengaged.
3. Adjust the needle settings as described under
Adjustments.
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