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SECTION 6A
FUEL SYSTEMS AND GOVERNORS
Condition
1. Black sooty exhaust smoke*, engine sluggish.
2. Engine misses and backfires at high speed.
3. Engine starts and then stops under cold weather
conditions.
4. Engine runs roughly or stalls at idle speed.
tinue, adjust the carburetor immediately.
* if black exhaust smoke is noted, check the air cleaner first. An apparent "over rich" mixture can actually be
caused by a clogged air cleaner element.
If after element is replaced, black smoke or other problems con-
Possible Cause/Probable Solution
1. Main fuel mixture too rich. Tum main fuel adjusting
needie in (clockwise).
2. Main fuel mixture tdo lean. Tum main fuel adjusting
needle out (counterclockwise).
3. Main fuel mixture too lean. Turn main fuel adjusting
needie out (counterclockwise).
4. Idle speed too low or improper idle fuel mixture.
Tum idle speed adjusting screw, then idle fuel ad-
justing needle.
1. Stop the engine. Turn the main fuel and idle fuel
adjusting needles in (clockwise) until they bottom
lightly.
NOTE:
The ends of the main fuel and idle fuel ad-
justing needles are tapered to critical di-
mensions.
Damage to needles and seats
will result if the needles are forced.
Main Fuel
Needle
CS
Idle
Fuel
Needle
Figure 6A-5. Kohler-Built Adjustable Jet Carburetor.
2. Preliminary Settings: Turn the main fuel and idle
fuel adjusting needles out (counterclockwise)
from lightly bottomed as follows:
2-1/2 Turns
1 Turn
Main Fuel Needle
Idle Fuet Needle
3. Start the engine and run at half-throttle for 5-10
minutes to warm up. Engine must be warm before
making final settings (Steps 4-6).
4. Final Setting - Main Fuel: Place throttle in wide
open position; and if possible, place engine under
load. Tum main fuel adjusting needle out (coun-
terclackwise) from preliminary setting until the en-
gine speed decreases (rich). Note the position of
the needle.
Naw tum the adjusting needie In (clockwise). Tne
engine speed may increase, then it will decrease
as the needle is tumed in (lean). Note the posi-
lion of the needle.
Set the adjusting need!e midway between the rich
and lean settings noted.
Refer to Figure 6A-6.
Lean
Adjust To
7]
Midpoint
|
Figure 6А-6.
Carburetor Adjustment.
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