FUEL
SYSTEM
CARBURETOR
(GASOLINE)
Downdraft and sidedraft carburetors are used on the two cylinder engines. Carburetors are
adjusted
in
the factory,
and under normal conditions, require no further adjustment unless one
of the
following conditions
is
noted:
Before readjusting carburetor,
check condition of air cleaner
--
an "over-
rich
"
mixture is often caused by a poorly serviced, clogged air cleaner element.
Also check for leak
-
ing intake manifold or poor ignition which could also cause some of the conditions.
CONDITION
POSSIBLE;
CAUSE/PROBABLE
REMEDY
A. Black, sooty exhaust smoke, engine
A.
Mixture too rich
-
readjust main fuel needle.
sluggish.
B.
Engine misses and backfires at high speed. B.
Mixture too lean
-
readjust main fuel needle.
C.
Engine starts, sputters and dies under
C.
Mixture too lean
-
turn main fuel adjustment
cold weather starting.
1/4
turn counterclockwise.
D.
Engine runs rough or stalls at idle speed.
D.
Idle speed too
low
or improper idle adjust
-
ment
-
readjust speed then idle fuel needle
if
needed.
Two types of sidedraft carburetors are used. One type has external adjustments for Main Fuel
and Idle Fuel. The other is a fixed main jet type which has an external adjustment for the Idle Fuel
needle only. On fixed jet carburetors, main fuel adjustment is possible only by changing to a discharge
jet of different size.
If
an engine with fixed jet carburetor
is
to be operated at high altitudes (above
6000 feet) the standard jet should be replaced by a special 6000' jet. Another special jet
is
available
for operating at
12,000 feet above sea level. See parts manual for correct part numbers.
Carburetor Adjustment:
Maximum power and efficiency are possible only with proper carburetion.
Improper carburetor adjustment can lead to overheating,
fouled spark plug, excessive valve wear and
other problems.
Do
not neglect carburetor if any of the above problems persist. The following adjust
-
ment procedure
is
for sidedraft and downdraft gasoline carburetors
-
-
see Special Fuel System Section
for procedure on other types of carburetors.
STEP
1
-
Stop engine and carefully turn Main Fuel and Idle Fuel Needle adjusting screws all the way
in (clockwise direction) until they bottom gently
--
DO
NOT
FORCE SCREWS as this will
damage the needle valves.
lULt
tUtL
IDLE
FUEL
ADJUSTMENT
TURNS OPEN]
ADJUSTMENT
(2
TURNS OPEN)
ADJUSTMENT
FIGURE
4
-
1
ADJUSTMENTS, TYPICAL SIDEDRAFT FIGURE 4
-
2
-
-
ADJUSTMENTS, FIXED MAIN JET CARBURETOR
CARBURETOR
(K482.
K532
)
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