TESTING AND ADJUSTING
ture, again check for stable operation.
engine TESTING AND ADJUSTING Service Manual for
necessary. DO NOT fully close the needle valve. This
the fuel setting procedure.
can cause excessive overshoot on startup, or load
LOW IDLE ADJUSTMENT
1. Low idle stop screw. 2. Plate.
NEEDLE VALVE ADJUSTMENT
Low and high idle speed stop screws are on the
With the engine at normal operating temperature
left side of the governor case, and are adjusted from the
and no load, operate the engine at low idle speed. Open
outside of the governor.
the governor compensation needle valve and let the
governor increase and decrease engine speed (hunt) for
The low idle speed stop screw is not covered,
a minimum of 30 seconds to remove air from the system.
and can be adjusted without breaking the wire seal (wire
If the governor does not hunt, rapidly move the speed
and seal not shown).
control shaft to change governor stability.
The high idle speed stop screw is covered by
After 30 seconds and the air is removed from the
plate (2). The plate is held to the governor case with two
system, turn the needle valve in (clockwise) until the
wire lock bolts. Install a wire and seal on the high idle
engine runs smoothly.
speed adjustment cover bolts to prevent tampering.
With the engine running at medium (mid) speed,
A 1/8 inch hex wrench is used for turning both
load the engine (at least one-quarter load) to find the
low and high idle speed stop screws.
stability of the setting. Quickly remove the load. A slight
overshoot of speed is ideal, as it reduces response time.
The engine speed should return to smooth steady
The engine may overspeed due to improper
operation. If it does not have a slight overshoot and
reassembly or adjustment, which could result in
return to a smooth steady operation, adjust the needle
personal injury, loss of life, and/or property damage.
valve and repeat the above procedure.
Be prepared to stop the engine by activating the
Governor terminal shaft "jiggle" or surge is an
emergency air shut off or closing the air inlets.
Too little compensation (needle valve out
Torsional vibration (pulsing);
Improperly aligned governor drive spline;
A binding or loose fuel control mechanism.
LOW AND HIGH IDLE ADJUSTMENTS
NOTE: Make sure the engine fuel setting is correct
before low and high idle adjustments are made. See the
HIGH IDLE ADJUSTMENT
3. High idle stop screw.