11
Kohler Carburetor Adjustment
1. With the engine stopped, turn the fuel adjusting
needles
in
(clockwise) until they bottom
lightly
.
NOTE: The tip of the idle fuel and main fuel
adjusting needles are tapered to critical
dimensions. Damage to the needles and
the seats in carburetor body will result if
the needles are forced.
2.
Preliminary Settings:
Turn the adjusting needles
out
(counterclockwise) from lightly bottomed as
follows:
Kohler Adjustable Jet
5.
Low Idle Fuel Needle Setting:
Place the throttle
into the
idle
or
slow
position.
Use the same procedure used for the main fuel
needle and set the adjusting needle
midway
between the rich and lean settings.
6.
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
manufacturer's recommendations. The
recommended low idle speed for basic
engines is 1200 RPM. To ensure best
results when setting the low idle fuel
needle, the low idle speed must not
exceed 1500 RPM.
Walbro Carburetor Adjustment
In general, turning the adjusting needles
in
(clockwise)
decreases the supply of fuel to the carburetor. This
gives a
leaner
fuel-to-air mixture. Turning the adjusting
needles
out
(counterclockwise) increases the supply of
fuel to the carburetor.
Carburetors on certified engines have a fixed (non-
adjustable) main jet. In steps 1 and 2, perform only
what pertains to the idle fuel needle. Skip step 4.
3. 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 4-6).
4.
Main Fuel Needle Setting:
This adjustment is
required for adjustable main jet carburetors only. If
the carburetor is a fixed main jet type, refer to
Walbro adjustment.
Place the throttle into the
fast
position. If
possible, place the engine under load.
Turn the main fuel adjusting needle
out
(counterclockwise) from the preliminary setting
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 settings. See Figure 8.
Figure 9.
1. With the engine stopped, turn the adjusting
needle(s)
in
(clockwise) until it bottoms
lightly
.
NOTE: The tips of the fuel adjusting needles are
tapered to critical dimensions. Damage to
the needles and the seats in carburetor
body will result if the needles are forced.
Low Idle
High Idle
M8
1-1/4 turns
2 turns
M12
2-1/2 turns
2 turns
M16
2-1/2 turns
3-1/2 turns
Lean
Rich
Adjust to
Midpoint
Figure 8.
Low Idle Speed
Adjusting Screw
Low Idle Fuel
Adjusting Needle
High Idle Fuel
Adjusting Needle
(Adj. Jet Carbs. Only)
