TM 5-4310-382-13
3-21. CARBURETOR - Continued.
e. Adjustment.
NOTE
All carburetor adjustments must be made with air cleaner installed onto
carburetor.
(1) Start engine and run until warmed up.
(2) Adjust governor speed control linkage to open throttle to achieve highest engine speed.
(3) Turn high speed needle valve (4) clockwise until engine begins to slow down (fuel mixture too lean).
(4) While counting number of turns on high speed needle valve (4), rotate it counterclockwise until engine speeds
up (fuel mixture too rich) and then begins to slow down again.
(5) Turn high speed needle valve clockwise again until half of the number of turns counted in step (5) is reached.
High speed needle valve is now adjusted.
(6) Disconnect governor speed control linkage and close throttle to achieve lowest engine speed.
(7) Adjust idle speed adjusting screw (1) on carburetor (3) until engine is running at 1,750 RPM.
(8) Turn idle speed needle valve screw (2) clockwise until engine begins to slow down (fuel mixture is too lean).
(9) While counting number turns on idle speed needle valve screw (2), rotate it counterclockwise until engine
speeds up and then slows down again (fuel mixture too rich).
(10) Turn idle speed needle valve screw (2) clockwise again until half the number of turns counted in step (9) is
reached. Idle speed needle valve is now adjusted.
Figure 3-15. Carburetor Adjustment.
3-40
