CARBURETOR MIXTURE
ADJUSTMENT
9.9/15
MODELS
IMPORTANT: Changing original factory fuel
mixture calibrations beyond the limits allowed by
the tamper resistant device
is
a violation of federal
law.
Any
needle valve adjustments beyond preset
limits become the responsibility of the servicing
technician andlor the owner. Refer
to
Emissions
Compliance
on
p.
150.
If
the carburetor body cover assembly must
be
replaced;
or,
if the original calibration settings are
lost, the following procedure can
be
used
to
make
adjustments based
on
engine performance.
Adjustment of the tamper resistant
needle valve
requires a special
Torx
Screwdriver,
PIN
351204.
Start the engine and
run
it
in
FORWARD at one-
half throttle. Allow the engine to reach normal
operating temperature.
Tiller Models
Face the steering handle. Turn the idle speed
adjustment knob counterclockwise to
lowest
SLOW
speed position.
FUEL SYSTEM
CARBURETOR MIXTURE ADJUSTMENT
Run
the engine
at
slow speed (700 to 800 RPM)
and adjust the
low-speed needle until the highest
consistent
RPM
is
attained. Allow
15
seconds
after each adjustment for
the
engine
to
respond.
1
Reduce engine speed and turn the idle speed
adjustment to
allow the engine
to
run
at a mini- 6
mum of 650
RPM
in
FORWARD.
Run
the engine
in
gear near full throttle for one
minute.
Quickly reduce speed to SLOW (700 to
800 RPM) and shift into NEUTRAL. The engine
should continue
to
run
smoothly.
If the engine stalls or pops, the mixture
is
too lean.
Turn the needle counterclockwise 1/16 turn. Allow
15
seconds after each adjustment for the engine
to
respond.
Do
the previous step again to make
sure the mixture adjustment
is
correct.
If
the engine does not respond
to
adjustments,
check it for other problems. Make sure gasoline
is
of good quality and mixed with the proper amount
of
oil.
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161
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