5.6
Section 5
Fuel System and Governor
Low Idle Speed (RPM) Adjustment
1.
Low Idle Speed (RPM) Se
tt
ing
: Place the thro
tt
le
control in the
idle
or
slow
position. Set the low
idle speed approximately
300 RPM
*
less
than
the intended or speci
fi
ed Governed Idle Speed,
by turning the low idle speed adjusting screw
in or out. Check the speed using a tachometer.
IMPORTANT: The Governed Idle Speed
Adjustment must follow any rese
tt
ing of the
Low Idle Speed.
*NOTE: The actual low idle speed depends on
the application. Refer to the equipment
manufacturer’s recommendations.
The low idle speed for basic engines
is
1200 RPM
. To ensure best results
when se
tt
ing the low idle fuel needle,
the low idle speed should be
1200 RPM
(± 75 RPM
).
Figure 5-5. Carburetor Adjustment Locations.
Low Idle Fuel Adjustment
NOTE: Engines will have
fi
xed low idle or limiter
caps on the two idle fuel adjusting needles.
Step 3 can only be performed within the
limits allowed by the cap. Do not a
tt
empt to
remove the limiter caps.
1. Start the engine and run at half thro
tt
le for 5 to 10
minutes to warm up. The engine must be warm
before doing Steps 2, 3, and 4.
2. Place the thro
tt
le control into the
idle
or
slow
position. Adjust the low idle speed to 1200 RPM.
Follow the Adjusting the Low Idle Speed (RPM)
procedure.
3.
Low Idle Fuel Needle(s) Se
tt
ing:
Place the
thro
tt
le into the
idle
or
slow
position.
a. Turn one of the low idle fuel adjusting
needles out (counterclockwise) from the
preliminary se
tt
ing until the engine speed
decreases (rich). Note the position of the
needle. Now turn the adjusting needle in
(clockwise). The engine speed may increase,
then it will decrease as the needle is turned
in (lean). Note the position of the needle. Set
the adjusting needle midway between the
rich and lean se
tt
ings. See Figure 5-6.
b. Repeat the procedure on the other low idle
adjustment needle.
4. Recheck/adjust the Low Idle Speed (RPM) to the
speci
fi
ed se
tt
ing.
Figure 5- 6. Optimum Low Idle Fuel Settings.
Governed Idle System
A governed idle control system is used to maintain a
desired idle speed regardless of ambient conditions
(temperature, parasitic load, etc.) that may change.
An outer secondary spring connected between the
governor lever and the governed idle adjuster on the
main bracket establishes the governed idle speed. See
Figure 5-7.
Governed Idle Speed Adjustment
1. Make sure the governed idle spring is in the outer
hole in the governor lever and the hole in the
governed idle (outer) adjuster. See Figure 5-7.
2. Make sure the governor spring is in the inner slot
of the governor lever and the hole in the high
speed (inner) adjuster. See Figure 5-7. Pull the
governor lever
away
from carburetor to the limit
of its travel and check that the governor spring is
loose and not under any tension. See Figure 5-8.
Turn the high-speed (RPM) adjustment screw
counter-clockwise
(if required) until spring is
loose.
Lean
Rich
Adjust to
Midpoint
Lean
Rich
Adjust to
Midpoint
Left Side
Right Side
Low Idle Fuel Adjusters
(with Limiters)
Low Idle
Speed (RPM)
Adjustment
Screw
Bowl
Vent
Summary of Contents for Comand Pro CH1000
Page 1: ...SERVICE MANUAL HORIZONTAL CRANKSHAFT CH940 CH1000...
Page 2: ......
Page 4: ......
Page 30: ...4 4 Section 4 Air Cleaner and Air Intake System...
Page 52: ...6 6 Section 6 Lubrication System...
Page 96: ...8 16 Section 8 Disassembly...
Page 110: ...Section 9 Inspection and Reconditioning 9 14...
Page 140: ...10 30 Section 10 Reassembly...
Page 141: ......