Engine Service Manual

Fuel System
3332 690 03 Rev. I KohlerEngines.com
Carburetor Adjustments
NOTE: Carburetor adjustments should be made only
after engine has warmed up.
Carburetor is designed to deliver correct fuel-to-air
mixture to engine under all operating conditions. Main
fuel jet is calibrated at factory and is not adjustable. Idle
fuel adjusting needles are also set at factory and are not
adjustable.
Idle Speed (RPM) Adjustment
1. Hold governor lever away from carburetor so throttle
lever is against idle speed (RPM) adjustment screw
of carburetor. Start engine and allow to warm up,
then adjust screw to set approximately 1450 RPM.
Check speed using a tachometer. Turn adjustment
screw (inner) clockwise (in) to increase or
counterclockwise (out) to decrease speed.
2. Release governor lever and check that throttle lever
is in idle position. Obtain equipment manufacturer’s
recommended idle speed (1750 RPM). All engines
have a bendable tab that is used to set this speed. A
pliers should be used to bend this tab to achieve
recommended speed. Governed idle speed (RPM) is
typically 300 RPM (approximate) higher than low idle
speed.
3. Move throttle lever to wide-open/full throttle position
and hold in this position. Turn high speed screw to
obtain intended high speed no-load RPM. Governed
idle speed must be set before making this
adjustment.
High Speed (RPM) Adjustment
1. With engine running, move throttle control to fast.
2. Turn inner adjustment screw outward to decrease, or
inward to increase RPM speed.
Carburetor Servicing
WARNING
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
Before working on engine or equipment, disable
engine as follows: 1) Disconnect spark plug lead(s). 2)
Disconnect negative (–) battery cable from battery.
NOTE: Main and slow jets are fi xed and size specifi c
and can be removed if required. Fixed jets for
high altitudes are available.
● Inspect carburetor body for cracks, holes, and other
wear or damage.
● Inspect fl oat for cracks, holes, and missing or
damaged fl oat tabs. Check fl oat hinge and shaft for
wear or damage.
● Inspect fuel inlet needle and seat for wear or damage.
● Inspect spring loaded choke plate to make sure it
moves freely on shaft.
Float Setting (Keihin Only)
A
A 12 mm (0.472 in.)
NOTE: Inlet needle center pin is spring loaded. Make
sure fl oat assembly rests against fuel inlet
needle, without depressing center pin.
1. Perform removal procedures for appropriate air
cleaner and carburetor outlined in Disassembly.
2. Clean exterior surfaces of dirt or foreign material
before disassembling carburetor. Remove bowl
retaining screws, or solenoid assembly, and carefully
separate fuel bowl from carburetor. Do not damage
fuel bowl O-rings. Transfer any remaining fuel into
an approved container. Save all parts.
3. Remove fl oat pin (some carburetors may have a
screw which requires removal), and inlet needle.
Seat for inlet needle is not serviceable and should
not be removed.
4. Remove two screws securing top cover, gasket, and
ground lead (Keihin carburetors only). Discard
gasket and screws only.
5. Remove idle speed adjusting screw and spring from
carburetor. Discard parts.
6. Clean carburetor bowl and inlet seat areas as
required.
7. Carefully remove main jet from carburetor. After
main jet is removed, on some carburetors, main
nozzle can be removed through bottom of main
tower. Note orientation/direction of nozzle. Save
parts for cleaning and reuse.
8. Position of slow jet varies and is removable only on
some styles of carburetors. See correct illustration
for corresponding style of carburetor showing
location. Save parts for cleaning and reuse unless a
jet kit is also being installed. Clean slow jet using
compressed air. Do not use wire or carburetor
cleaner.
9. Carburetor is now disassembled for appropriate
cleaning and installation of parts in overhaul kit.
Further disassembly is not necessary. Throttle shaft
assembly, fuel inlet seat and idle fuel adjustment
screw are non-serviceable items and should not be
removed. Choke shaft assembly is serviceable,
however it should not be removed unless a choke
repair kit will be installed.