TM 5-4310-335-14
Table 5-1. TROUBLESHOOTING (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
b. Remove screw and disconnect throttle lever from shaft.
c. Remove nut (2) and remove carburetor and gasket from intake manifold.
d. Remove screw (2) and remove air cleaner duet elbow from carburetor.
e. Remove screw (2) and remove throttle housing from carburetor. Remove rear cover and gaskets from
throttle housing.
f. Spread control rod clevis and remove throttle lever.
g. Remove screw and remove throttle control from carburetor. Remove bolts and remove the intake
manifold. Remove screws and remove the exhaust manifold-muffler. Loosen nuts on breather line
and remove the line from air cleaner to cylinder head. Remove the rocker arms, cylinder head
pushrods, and pushrod housings, as follows:
a. Remove nuts (4).
b. Remove clip and slide shaft from cylinder head.
c. Remove nuts and adjusting screw.
d. Remove push rod housing.
NOTE
Remove push rods and packing from housings.
e. Remove cylinder head.
NOTE
Remove and discard cylinder head gasket.
NOTE
Remove needle bearings from rocker arm shaft.
WARNING
Dry cleaning solvent, P-D-80 or P-S-661, used to clean parts is potentially
dangerous to personnel and property. Avoid repeated and prolonged skin
contact. Do not use near open flame or excessive heat. Flash point of
solvent is 100 (39 ) - 138 (59 ).
F
C
F
C
Inspect parts for defects, damage, cracks, breaks deterioration. Warps and dents.
Remote carbon deposits, grease, other materials or sum. Remove any burrs or
nicks. Clean parts with dry cleaning solvent, P-D-680.
Dry parts thoroughly with compressed filtered air and place on clean shop towels or
cloths and tag. Replace parts if damaged or defective with standard replacement
parts or equivalent.
Cheek the valve springs for proper compression. Replace a damaged or defective
valve spring.
NOTE
The valve springs should test to the following dimensions:
Free length
1.275 in
Load at compressed length of 1.095 in. = 20 lbs 1 lb.
Load at compressed length of 0.880 in. = 44 lbs 2 lbs.
Grind valves and lop them to the seat inserts Individually to insure a sealed fit
between the valve and valve inserts. Install the valves and valve springs into the
cylinder head.
Install the cylinder head, pushrod housings onto the engine. Install new head
gaskets and packings. Install the breather line to air cleaner and cylinder head.
Install the manifold muffler. Install the intake manifold. Install the carburetor and
throttle controls.
a. Remove screw (2) and remove throttle control housing cover.
b. Remove screw and disconnect throttle lever from shaft.
c. Remove nut (2) and remove carburetor and gasket from intake manifold.
d. Remove screw (2) and remove air cleaner duet elbow from carburetor.
e. Remove screw (2) and remove throttle housing from carburetor. Remove rear cover and gaskets from
throttle housing.
f. Spread control rod clevis and remove throttle lever.
g. Remove screw and remove throttle control from carburetor.
Adjust the carburetor as follows:
a. With engine stopped turn main adjustment needle and Idle adjustment needle fully clockwise to close.
b. Turn main adjustment needle three-quarters of a turn counterclockwise, and idle adjustment needle
one-half turn counterclockwise. Start engine and ran until warn.
misfires or seems low in power, open main exhaust needle. Adjust main adjustment needle until
engine delivers maximum power with minimum of exhaust smoke.
d. If engine application has a throttled speed adjustment, regulate idle mixture in a similar manner.
e. Regulate engine idle rpm by turning idle speed regulating screw clockwise or counterclockwise.
5-2
