CARBURETOR
ADJUSTMENT
-I
Lack of power and black sooty exhaust smoke usually indicates that fuel mixture is too rich. An
"overrich" mixture may also be caused by a clogged air cleaner--check this before readjusting carbu-
retcH. Fuel mixture nlay be too lean if engine "skips" or backfires. Note that an overrich condition
cou1d a1so be caused by an inlproperly adjusted choke.
Main Fuel Adjustment: For preliminary setting, turn MAIN FUEL screw in clockwise direction until it
bottoms lightly (do not force) then back out Z turns. With engine thoroughly warmed up and running at
1800 RPM· and full load; turn MAIN FUEL screw in until engine slows down (lean setting) then turn
screw out until engine regains speed and then starts to slow down (overrich setting). Turn screw back
in until it is positioned halfway between lean and overrich settings--when properly adjusted, engine
will operate with steady governor action.
Idle Adjustrnent: On generator set app1ications, the idle systenl functions only as the engine UHnes up
thru idle range to 1800 RPM. For this reason, idle system has o'11y a mo~entary effect. To adjust.
stop engine then turn IDLE FUEL screw all the way in (clockwise) until it bottoms lightly (do not force
screw), then back out 1-1/4 turns--no further adjustment is needed.
MOVE LEVER IN DIRECTION
OF ARROW TO INCREASE CHOKE
MAIN FUEL
ADJUSTMENT~
(2 TURNS) ~
CHOKE PLATE
IDLE FUEL
ADJUSTMENT
(1-1/4 TURNS)
#43 DRILL
(.089") _
----......... F1
II
LEVER
CLAMP
BOLT~
t
----- CHOKE
LEV ER
ARM
NOTCH
IN
BASE
FIGURE 5 - CARBURETOR ADJUSTMENTS
FIGURE 6 - AUTOMATIC CHOKE ADJUSTMENT
AUTOMATIC
CHOKE
Chokes are set at the factory but may have to be readjusted to suit local conditions. Remove air
cleaner from carburetor to observe position of choke plate. Choke adjustment must be made on cold
engine. If starting in extreme cold, choke should be in full closed position before engine is started. A
lesser degree of choking may be needed in milder temperatures. If adjustment is required, proceed as
follows: .
1. Move choke arm until hole in cross shaft lines up with slot in bearings.
Z. Insert #43 drill (.089) thru hole and push all the way down to engine manifold to engage in
notch in base of choke unit (see accompanying figure).
3. Loosen clamp bolt on choke lever, push arm upwardto move choke plate toward closed
position for increased choke or away to decrease choking effect. When properly positioned,
tighten clamp bolt then remove drill.
4. After replacing air cleaner, check for evidence of binding in linkage--correct if necessary.
Be sure choke is fully open when engine is at normal operating temperatures.
5
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