TM 5-4310-276-14
Table 4-2. Troubleshooting (cont)
Malfunction
Test or Inspection
Corrective Action
NOTE
Eliminate surging or poor speed regulation by adjusting the idle adjustment needle on carburetor.
(3) increase speed until normal operating temperature returns.
c. Close drain valve on air tank.
Step 3. Inspect for dirty or obstructed fan screen.
Clean the fan screen.
Step 4. Inspect for restricted cylinder cooling fins
Clean cylinder cooling fins.
4. ENGINE LACKS POWER.
Step 1. Check for improper fuel mixture.
Drain fuel tank and fill with correct fuel. Adjust carburetor.
a. Using figure 4-7 as a guide, adjust the carburetor.
b. With engine stopped, turn main adjustment needle and idle adjustment needle fully clockwise
to close.
c. Turn main adjustment needle three-quarters of a turn counterclockwise, and idle adjustment
needle one-half turn counterclockwise. Start engine and run until warm.
d. Apply load and observe engine exhaust. If exhaust is black, close main adjustment needle. If en-
gine misfires or seems low in power, open main adjustment needle. Adjust main adjustment needle until
engine delivers maximum power with minimum of exhaust smoke.
e. If engine application has a throttle speed adjustment, regulate idle mixture in a similar manner.
f. Regulate engine idle rpm by turning idle speed regulating screw clockwise or counterclockwise
enough to keep the engine running smoothly.
Step 2. Check for clogged exhaust ports
Clean exhaust ports.
Step 3. Inspect for improper timing.
Retime engine.
a. Contact adjustment.
(1) Remove accessory case cover.
(2) See figure 4-10 for point adjustment.
(3) Rotate engine flywheel until the cam follower is positioned on the highest point of the
ignition cam.
(4) Measure the point gap with a feeler gauge. Adjust to measure 0.018 in. (0.457 mm).
(5) Loosen the screws (2) that secure the stationary plate and move the plate until the cap is
correct.
(6) Tighten screws, remeasure gap, and readjust if necessary.
b. Ignition timing.
(1) See figure 4-15 for ignition timing.
4-22
