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Carburetor Adjustments - Craftsman WEEDWACKER 358.798441 Operator's Manual

21 cc/1.3 cu. in. 2-cycle engine 17" semi-automatic head gas weedwacker

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Table of Contents
SERVICE AND ADJUSTMENTS
Carburetor
adjustment
is critical and if done improper-
ly can permanently
damage
the engine as well as the
carburetor.
Please read all instructions
and consult the
Troubleshooting
section
of this manual before begin-
ning
this
process.
If the engine
does
not operate
according
to these
instructions
after
repeating
the
adjusting
steps, do not use the unit. For further assis-
tance, please
call our customer
assistance
hotline at
1-800-235-587&
MIXTURE SCREW (WITH MMITER CAP)
_1_
WARNING:
MAKE CARBURETOR ADJUSTMENTS WITH
THE LOWER END SUPPORTEDTO PREVENT
SEMI-AUTOMATIC HEAD FROM CONTACTING
ANY OBJECT. HOLD UNIT WITH YOUR HAND.
THE SEMI-AUTOMATIC HEAD WILL BE SPIN-
NING DURING MOST OF THIS PROCEDURE.
WEAR YOUR PROTECTIVE EQUIPMENT AND
OBSERVE ALL SAFETY PRECAUTIONS.
IN MIXTURE ADJUSTMENT, RECHECK IDLE
SPEED
AFTER EACH ADJUSTMENT. THE
SEMI-AUTOMATIC HEAD MUST NOT MOVE AT
IDLE SPEED°
If engine does not start, it may be flooded If in doubt read
the section on flooded engine in the starting section of this
manual prior to beginning any adjustments.
The carburetor has been adjusted at the factory for sea
level conditions. Ad ustments may become necessary if the
unit is used at significantly higher altitudes or if you notice
any of the following conditions:
- Engine will not idle See "Idle Speed Adjustment" and
"Mixture Speed Adjustment".
o Engine dies or hesitates when it should accelerate See
"Acceleration Check".
• Loss of cutting power which is not corrected by air filter
cleaning See "Mixture Speed Adjustment"
NOTE: There are two adjustments on the carburetor
= The Idle Speed Adjustment.
° The Mixture Adjustment..
CARBURETOR
PRESETS
(Fig. 28)
If your engine will not start due to suspected impropercar-
buretor adjustment, the following presets may be required
If used, it is recommended that all steps withing the adjust-
ment procedure be completed in order to assure a proper-
ly set carburetor. If presets are not needed, proceed to sec-
tion "Idle Speed Adjustment".
When making adjustments, be careful not to force the plas-
tic limiter caps beyond the stops or damage will occur
Very
small adjustments can affect engine performance. It is
important to make slight adjustments and test performance
before proceeding, Each adjustment should be no more
than 1/16th of a turn.
• Turn the mixture adjustment fully counterclockwise to the
limiter cap stops
= Turn idle speed adjustment clockwise one full turn
• If engine fails to start after performing carburetor presets,
the unit may be flooded. Review the "Difficult Starting"
section of the manual If problems continue, call the 1-
800 number listed on the front cover of this manual for
further assistance.
• Start the engine and operate for three (3) minutes to
warm up Go to "Adjusting Procedure"
IDLE SPEED SCREW
Figure 28
ADJUSTING
PROCEDURE
IDLE SPEED ADJUSTMENT
• Allow the warm engine to idle
• Adjust the Idle Speed until the engine continues to run
without stalling and without the semi-automatic head
turning.
- Turn screw clockwise to increase engine speed if
engine stalls or dies
- Turn screw counterclockwise to slow engine down.
• Follow instructions in "Acceleration Check"
• No further adjustments are necessary if performance is
satisfactory.
MIXTURE ADJUSTMENT
• Support the lower end so the semi-automatic line head is
off the ground and will not make contact with any object
Be sure the trimmer line is extended to the maximum
length allowed by the line limiter.
• Start the engine. Allow engine to idle, then squeeze
throttletrigger fully.
NOTE: Perform steps below at full throttle.
• Turn mixture screw counterclockwiseto the limiter cap
stop
Run engine at full throttle for 30 seconds
If engine Is running rough, turn mixture screw clockwise
in 1/16th turn increments until engine just starts to run
smoothly
• Do not attempt to adjust screw beyond stops as damage
will occur.
• After completing adjustments, check for acceleration.
• If the unit accelerates and runs smoothly, no further
adjustments
are
necessary.
If not,
proceed
to
"Acceleration Check".
ACCELERATION CHECK
• Allow engine to idle
• Squeeze trigger fully
- If performance
is satisfactory (engine accelerates
smoothly), no further adjustments are necessary.
- If the engine does not accelerate smoothly, turn the
mixture screw counterclockwise a small amount (no
more than the width of the slot in the ad usting screw)
• Repeat step above unt I smooth acceleration is obtained
Do not attempt to adjust the screw beyond the stop as
damage will occur.
NOTE: It may be necessary
to repeat "Idle speed
Adjustment" through "Acceleration Check;' to obtain correct
adjustments,
-19-

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