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TROUBLESHOOTING & REPAIR
F-28 F-28
COMMANDER 500
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ENGINE THROTTLE ADJUSTMENT TEST (CONTINUED)
6. If either of the readings is incorrect, adjust
the throttle as follows:
Adjust HIGH IDLE: Use the 10mm wrench
to loosen the locking nut. See Figure F.8
for location of the adjusting screw and lock-
ing nut. Turn the threaded screw counter-
clockwise to increase the HIGH IDLE
speed. Adjust the speed until the tach
reads between 1890 and 1910 RPM.
Retighten the locking nut.
Adjust LOW IDLE: First make sure there is
no load on the machine. Set the IDLE
switch to AUTO and wait for the engine to
change to low idle speed. Use the 10mm
wrench to loosen the solenoid lever arm
locking nut. See Figure F.9. Adjust the col-
lar, to change the amount of throw in the
lever arm, until the tach reads between
1450 and 1500 RPM. Retighten the locking
nut.
Frequency Counter Method
1. Plug the frequency counter into one of the
115 VAC auxiliary receptacles.
2. Start the engine and check the frequency
counter. At HIGH IDLE (1900 RPM), the
counter should read 63 Hz. At LOW IDLE
(1475 RPM), the counter should read 49
Hz. Note that these are median measure-
ments; hertz readings may vary slightly
above or below.
3. If either of the readings is incorrect, adjust
the throttle as follows:
Adjust HIGH IDLE: Use the 10mm wrench
to loosen the locking nut. See Figure F.8
for location of the adjusting screw and lock-
ing nut. Turn the threaded screw counter-
clockwise to increase the HIGH IDLE
speed. Adjust the speed until the frequen-
cy reads 63 Hz. Retighten the locking nut.
Adjust LOW IDLE: First make sure there is
no load on the machine. Set the IDLE
switch to AUTO and wait for the engine to
change to low idle speed. Use the 10mm
wrench to loosen the solenoid lever arm
locking nut. See Figure F.9. Adjust the col-
lar, to change the amount of throw in the
lever arm, until the frequency reads 49 Hz.
Retighten the locking nut.
Oscilloscope Method
1. Connect the oscilloscope to the 115 VAC
receptacle, according to the manufacturer’s
instructions. At HIGH IDLE (1900 RPM),
the waveform should exhibit a period of
15.8 milliseconds. At LOW IDLE (1475
RPM), the waveform should exhibit a period
of 20.3 milliseconds. Refer to the NORMAL
OPEN CIRCUIT VOLTAGE WAVEFORM
(115 VAC SUPPLY) HIGH IDLE - NO LOAD
in this section of the manual.
2. If either of these waveform periods is incor-
rect, adjust the throttle as follows:
Adjust HIGH IDLE: Use the 10mm wrench
to loosen the locking nut. See Figure F.8
for location of the adjusting screw and lock-
ing nut. Turn the threaded screw counter-
clockwise to increase the HIGH IDLE
speed. Adjust the speed until the period is
15.8 milliseconds. Retighten the locking
nut.
Adjust LOW IDLE: First make sure there is
no load on the machine. Set the IDLE
switch to AUTO and wait for the engine to
change to low idle speed. Use the 10mm
wrench to loosen the solenoid lever arm
locking nut. See Figure F.9 Adjust the col-
lar, to change the amount of throw in the
lever arm, until the period is 20.3 millisec-
onds. Retighten the locking nut.