Kohler Command CH620 - Manual (Page 15)

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The system requires an additional procedure for
setting the idle speed. If speed adjustments are
required proceed as follows.
1. Make any necessary speed or control adjustments
following the appropriate instructions covered in
this section.
2. Move the throttle control to the idle position. Hold
the governor lever away from the carburetor, or
hold the throttle lever so it is tight against the idle
speed adjusting screw, to negate the governor
activation. See Figure 19. Check the speed with a
tachometer and adjust it to 1500 RPM.
3. Release the governor lever and allow the engine to
return to the governed idle speed. Check it with a
tachometer against the equipment manufacturers
recommended idle speed. Governed Idle Speed
(RPM) is typically 300 RPM (approximate) higher
than the low idle speed. If adjustment is
necessary, bend the adjusting tab on the speed
control assembly to set. See Figure 18.
• If the fuel tank is equipped with a shut-off valve,
make sure it is open.
• If the engine is equipped with an in-line fuel filter,
make sure it is clean and unobstructed. Replace
the filter if necessary.
• Make sure fuel is reaching the carburetor. This
includes checking the fuel lines and fuel pump for
restrictions or faulty components, replace as
necessary.
• Make sure the air cleaner element is clean and all
air cleaner element components are fastened
securely.
If, after checking the items listed above, the engine is
hard to start, runs roughly, or stalls at low idle speed,
it may be necessary to adjust or service the
carburetor.
Adjust Carburetor
Models CH18-740
There are no accessible mixture adjustment screws on
the carburetor. The only setting which can be changed
is the low idle speed.
1. Start the engine and run at half throttle for 5 to
10 minutes to warm up. The engine must be
warm before making final settings (steps 2 and 3).
2. Low Idle Speed Setting: Place the throttle control
into the idle or slow position. Set the low idle
speed to 1200 RPM* (± 75 RPM) by turning the
low idle speed adjusting screw in or out. Check
the speed using a tachometer.
*NOTE: The actual low idle speed depends on the
application – refer to equipment
manufacturers recommendations. The
standard low idle speed is 1200 RPM.
3. If proper operation is not restored after adjusting
the low idle speed, carburetor servicing by an
authorized Kohler Engine Service Dealer may be
required.
Models with Governed Idle System
An optional governed idle control system is supplied
on some CH18-740 engines. The purpose of this
system is to maintain a desired idle speed regardless
of ambient conditions (temperature, parasitic load,
etc.) that may change. Engines with this feature
contain a small secondary spring connected between
the governor lever and the lower adjustment tab of
the main bracket. See Figure 18.
Figure 18. Governed Idle Spring Location.
Governed Idle
Spring
Tab
Hold Throttle Lever
Against Screw
Figure 19. Holding Throttle Lever Against Idle Stop
Screw.