Figure 3-4. Carburetor adjustment

TM 55-1740-200-14

3-28. CARBURETOR ADJUSTMENT. Adjust fuel

c. Check battery electrolyte with a hydrometer as

mixture and carburetor linkage as follows: (See figure

outlined below. If the reading between cells differs by

3-4.)

more than 0.020, replace the battery.

a. Start the engine and allow engine to warm up to

normal operating temperature.

All repairs shall be made with the ignition

switch in the OFF position and the parking

b. Set idle adjustment screw to maintain 450 to 500

brake set.

rpm engine idle speed.

Specific Gravity

State of Charge

Specific Gravity

Normal Climate

Tropical Climate

c. Adjust the idle mixture screw to the leanest

position that will allow maximum steady engine speed.

Fully Charged

1.225

1.280

Turn clockwise for lean mixture and counterclockwise for

1.230

75%

1.180

rich mixture.

1.180

50%

1.135

1.130

25%

1.090

d. The accelerating pump lever should be placed in

1.080

Discharged

1.040

proper position in accordance with climate conditions.

The short stroke position is for extremely warm weather

NOTE

or for altitudes above 2,500 feet, the medium stroke

position is for normal summer weather and the long

All hydrometer readings are based on 80F

stroke position is for extremely cold weather operation.

electrolyte temperature.

Figure 3-4. Carburetor adjustment

3-6