Engine Tune-Up
adjust the minimum speed adjusting bolt to retain the
5. Move the output shaft governor rocker shaft lever to
the maximum fuel position and retain it by moving
lever.
the speed adjusting lever to the full-speed position.
11. Recheck the output shaft maximum and minimum
Then move the output shaft governor lever and the
speeds and readjust the position of the speed adjusting
throttle control lever together to the maximum speed
bolts, if necessary.
position and retain there.
12. To check the unit for stability as affected by
NOTE: This operation closes the low speed gap
governor speed droop, move the speed adjusting shaft
which may require more torque than is
lever, with the engine operating at no load, to the
available from the torsion spring between the
maximum speed position. Then move the output shaft
above two levers. Thus, it is important that they
governor rod to cause a speed decrease of several
be held together, permitting no space between
hundred rpm. Release the rod and check for hunting
the throttle control lever pin and the arm of the
when the governor returns the engine to the maximum
output shaft governor lever.
speed setting. If the engine stabilizes in less than three
surges, the droop may be set too high; if the engine
6. Adjust the output shaft governor rod length until it
will just slide into the inner hole of the output shaft
does not stabilize in five surges, the droop may be set
too low. Set the speed droop as follows:
governor lever (Fig. 1). Then, increase the length of
the rod until there is approximately .020" clearance
a. If the engine hunts less than three surges, back off
between the stop pin and the output shaft governor
the inner speed adjusting spring eye bolt nut one
lever. Tighten the adjustment.
full turn and tighten the inner nut one turn to
retain the adjustment. If the engine hunts more
7. Adjust the governor operating lever return spring by
than five surges, back off the outer speed adjusting
retaining the rocker shaft lever in the full-speed
spring eye bolt nut one full turn and tighten the
position and increasing the tension on the spring by
outer nut one turn to retain the adjustment.
adjusting the eye bolt and nuts, until the tension of the
torsion spring is overcome and the throttle control
NOTE: The eye of the bolt must be in a
lever is moved against its stop in the idle position.
horizontal plane to avoid twisting the spring.
8. Move the output shaft governor speed adjusting
b. Reset the maximum engine no-load speed, if
lever to the minimum speed position and start the
necessary, as outlined in Steps 9 and 10.
engine.
c. Recheck the speed droop. The engine speed should
9. Advance the output shaft governor speed adjusting
be stable when the governor droop is 7-1/2% to
lever to the desired maximum output shaft speed and
10% of the full-load speed. For example, at an
adjust the maximum speed adjusting bolt to retain the
output shaft speed setting of 1800 rpm full load,
lever.
the output shaft speed droop should be 150 to 200
rpm. Therefore, the no-load output shaft speed
10. Move the output shaft governor speed adjusting
should be set at 1950 to 2000 rpm.
shaft lever to the desired minimum speed position and
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