High Altitude Operation; Governor - Kohler CH940-CH1000 Service Manual

Fuel System and Governor
Always use new gaskets when servicing or reinstalling
carburetors. Repair kits are available which include
new gaskets and other components. Service/repair
kits available for Keihin BK two-barrel carburetors and
affi liated components are:
18. Clean carburetor body, main jets, vent ports, seats,
etc., using a good commercially available carburetor
solvent. Keep away from plastic or rubber parts if
non-compatible. Use clean, dry compressed air to
blow out internal channels and ports. Do not use
metal tools or wire to clean orifi ces and jets. Inspect
and thoroughly check carburetor for cracks, wear, or
damage. Inspect fuel inlet seat for wear or damage.
Check spring loaded choke plate to make sure it
moves freely on shaft.
19. Install two main nozzles into towers of carburetor
body. End of main nozzles with two raised shoulders
should be out/down (adjacent to main jets). Make
sure nozzles are completely bottomed. Carefully
install main jets into towers of carburetor body on
appropriate side, as identifi ed when removal was
performed.
20. Make sure O-ring near bottom of each slow jet is
new, or in good condition. Align and insert two slow
jets into top of carburetor.
21. Install large fl at retaining washer and secure with
mounting screw, attaching ground lead if originally
secured by screw.
22. Install new idle speed (RPM) adjustment screw and
spring onto carburetor. Thread in until 3 or 4 threads
are exposed, as an initial adjustment.
23. Attach inlet needle to plastic tang of fl oat with wire
clip. Formed 90° lip should point up, with needle
valve hanging down.
24. Install fl oat and inlet needle down into seat and
carburetor body. Install new pivot pin through fl oat
hinge and secure with new retaining screw.
25. Hold carburetor body so fl oat assembly hangs
vertically and rests lightly against fuel inlet needle.
Inlet needle should be fully seated but center pin of
needle (on retainer clip end) should not be
depressed. Check fl oat height adjustment.
Be sure to measure from casting surface, not rubber
gasket, if still attached.
26. Correct fl oat height setting is 17 mm (0.669 in.) ± 1.5
mm (0.059 in.), measured from fl oat bottom to body
of carburetor. Replace fl oat if height is different than
specifi ed. DO NOT attempt to adjust by bending fl oat
tab.
27. When proper fl oat height is obtained, carefully
reinstall fuel bowl onto carburetor, using new
O-rings. Secure with four original screws. Tighten
screws to torque specifi cations.
28. Set the two idle mixture screws at the midpoint of
available adjustment as a preliminary setting.
29. Use the new mounting gaskets provided for the air
cleaner and carburetor. Reinstall the carburetor and
disassembled components following Reassembly
procedures.
26
30. Reconnect the spark plug leads and negative battery
cable. Start the engine and perform Low Idle Speed
and Low Idle Fuel Needle(s) settings as outlined in
the service manual.

High Altitude Operation

This engine may require a high altitude carburetor
kit to ensure correct engine operation at altitudes
above 1219 meters (4000 ft.). To obtain high
altitude kit information or to fi nd a Kohler
authorized dealer visit KohlerEngines.com or call
1-800-544-2444 (U.S. and Canada).
This engine should be operated in its original
confi guration below 1219 meters (4000 ft.) as damage
may occur if high altitude carburetor kit is installed and
operated below 1219 meters (4000 ft.).

Governor

Governed speed setting is determined by position of
throttle control. It can be variable or constant, depending
on engine application.
Governor is designed to hold engine speed constant
under changing load conditions. Most engines are
equipped with a centrifugal fl yweight mechanical
governor. Governor gear/fl yweight mechanism of
mechanical governor is mounted inside crankcase and is
driven off gear on camshaft. This governor design works
as follows:
● Centrifugal force acting on rotating governor gear
assembly causes fl yweights to move outward as
speed increases. Governor spring tension moves
them inward as speed decreases.
● As fl yweights move outward, they cause regulating pin
to move outward.
● Regulating pin contacts tab on cross shaft causing
shaft to rotate.
● One end of cross shaft protrudes through crankcase.
Rotating action of cross shaft is transmitted to throttle
lever of carburetor through external throttle linkage.
● When engine is at rest, and throttle is in fast position,
tension of governor spring holds throttle plate open.
When engine is operating, governor gear assembly is
rotating. Force applied by regulating pin against cross
shaft tends to close throttle plate. Governor spring
tension and force applied by regulating pin balance
each other during operation, to maintain engine
speed.
● When load is applied and engine speed and governor
gear speed decreases, governor spring tension moves
governor arm to open throttle plate wider. This allows
more fuel into engine, increasing engine speed. As
speed reaches governed setting, governor spring
tension and force applied by regulating pin will again
offset each other to hold a steady engine speed.
KohlerEngines.com 62 690 01 Rev. C