G424 Service Manual Adjustment and Troubleshooting171
3. Idling Speed Adjustment
Gasoline Carburetor
(1) Let engine warm up until the engine coolant
temperature rises to 80 to 95
°C (176 to 203°F)
(2) Back off the mixture adjussting screw (MAS)
3.5
L0.5 turns.
(3) Adjust the engine speed to the specified low idling
speed with the speed adjusting screw (SAS).
standard value : 700L25rpm
(4) Slowly turn down the mixture adjusting
screw(MAS) to a point where the engine speed
begins to decrease.
(5) After racing the engine two or three times (at
approx .2500 rpm), re-adjust the speed adjusting
screw to the point at which the engine rust at the
specified idling speed.
LP Gas Carburetor
See “Tests & Adjustments” of LP Fuel System Section.
4. Air Governor Adjustment
High speed adjustment
(1) Place all the hydraulic levers in the neutral
position.
(2) Depress the accelerator pedal all the way. (The
carburetor throttle valve will open fully.)
(3) While holding the adjust screw to prevent it from
turning, rotate the adjusting nut either clockwise or
counterclockwise to make the engine run at 2700
L 50 rpm.
Adjusting nut:
Clockwise rotation
Increases the engine speed (increases the
installed load of spring).
Counterclockwise rotation
Decreases the engine speed (decreases the
engine installed load of spring).
5. Anti-Hunting Adjustment
(1) Place all the hydraulic levers or powertrain in the
neutral position.
(2) Depress the accelerator pedal all the way. (The
carburetor throttle valve will open fully.)
(3) Slowly rotate the adjusting screw clockwise until
hunting disappears.
Adjusting screw:
Clockwise rotation
Increases spring tension (reduces the number
of active turns of spring).
Counterclockwise rotation
Reduces spring tension (increases the
number of active turns of spring).
Increasing the spring tension will eliminate hunting,
but an excessively high tension will change the
governor characteristics and produce some effects
on the output characteristics of the engine. It is,
therefore, imperative to limit the movement of the
adjusting screw to less than two turns from the
standard position.
(4) Clockwise rotation of the adjusting screw raises
the engine maximum speed. Rotate the push nut
counterclockwise to reduce the speed.
(5) Repeat anti-hunting adjustment two or three times
by alternately adjusting the push nut and the
adjusting screw until the best result is obtained.
(6) The number of active turns of spring should be
around 13~15 when the adjustment is finished.
SAS
MAS
6EN0836
Engine Speed (rpm)
Out put (PS)
Governor Characteristics
Larger spring
rigidity
Smaller spring
rigidity
6EN0835
Screw
Adjusting nut
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