Kohler K9J Service Manual page 39

Idle Fuel
Adjusting Needle
Figure 6-18. Fixed Main Jet Carburetor.
Lean
Adjust
To Midpoint
Figure 6-19. carburetor Adjustment.
CARBURETOR ADJUSTMENT
NOTE: The tip of the low idle fuel and high idle
fuel adjusting needles are tapered to critical di-
mensions. Damage to the needles and the seats
in carburetor body will result if the needles are
forced.
In general, turning the adjusting needles In (clock-
wise) decreases the supply of fuel to the carbure-
tor. This gives a leaner fuel-to-air mixture. Turning
the adjustfng needles out (counterclockwise) in-
creases the supply of fuel to the carburetor. This
gives a richer fuel-to-air mixture. Setting the
needles midway between the lean and rich posi-
tions will usually give the best results.
Adjust the carburetor as follows:
1. With the engine stopped, turn the low idle fuel
adjusting needle in (clockwise) until it bottoms
lightly.
2. Preliminary Settings: Turn the adjusting nee-
dles out (counterclockwise) from lightly bot-
tomed according to the table shown in Figure
6-20.
3. Start the engine and run at half throttle for five
to ten minutes to warm up. The engine must
be warm before making final settings (Steps 4,
5, 6, and 7).
4. High Idle Fuel Needle Setting: This adjustment
is required only for adjustable high idle (main)
jet carburetors. If the carburetor is
a
fixed main
jet type, go to step 5.
Place the throttle into the "fast" position. If possi-
ble, place the engine under load.
Turn the high idle fuel adjusting needle out (coun-
terclockwise) 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 6-21.
5. Low Idle Speed Setting: Place the throttle
control into the "idle" or "slow" position. Set
the low idle speed to 1200 rpm* (
+
or - 75
rpm) by turning the low idle speed adjusting
screw in or out. Check the speed using a ta-
chometer.
*NOTE: The actual low idle speed depends on the
application. Refer to the equipment manufacturer's
instructions for specific low idle speed settings.
The recommended low idle speed for Basic En-
gines is 1200 rpm. To ensure best results when
setting the low idle fuel needle, the low idle speed
must not exceed 1500 rpm.
6.13
II