Carburetor Adjustments; Service And Adjustments - Craftsman 358.795631 Operator's Manual

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SERVICE AND ADJUSTMENTS
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Carburetor adjustment is critical and if done improperly adjustment should be no more than the width of the slot in the
can permanently damage the engine as well as the car- adjusting screw.
buretor. Please read all instructions and consult the • Turn both of the mixture screws counterclockwise untflthey
Troubleshooting section of this manual before begin- stop.Do not attemptto adjustthe screw beyondthe stopsas
ning this process, if the engine does not operate accord- damage can occur.
ing to these instructions after repeating the adjusting • Turn the idle speedscrewclockwise1/2 turn.
steps, do not use the unit, For further assistance, please • Startthe engine and operatefor three )3) minutes to warm up.
call our customer assistance hotline at 1-800-235-5878. Go to"Adjusting procedure?
WARNING:
MAKE CARBURETOR ADJUSTMENTS
WITH THE LOWER END SUPPORTED TO
PREVENT BLADE FROM CONTACTING
ANY OBJECT. HOLD UNIT WITH YOUR
HAND.
THE BLADE WILL BE MOVING DURING
MOST OF THIS PROCEDURE, WEAR
YOUR PROTECTIVE EQUIPMENT AND
OBSERVE ALL SAFETY PRECAUTIONS.
IN "LOW SPEED MIXTURE ADJUST-
MENT," RECHECK IDLE SPEED AFTER
EACH ADJUSTMENT. THE CUTTING
BLADE MUST NOT MOVE AT IDLE SPEED.
If engine does not start, it may be flooded, tf in doubt, read the
sectionon flooded engine in the starting section of this manual
priorto beginning any adjustments.
If you are unsure about adjusting the carburetor or experience
any problem while attemptingthis process, please cal! the 1-800
number listed on the front cover of this manualfor further assis-
tance.
The carburetor has been adjusted at the factory for sea level
conditions. Adjustments may become necessary if the unit is
used at significantly higher altitudesor if you notice any of the
following conditions:
• Engine willnot continue to run at idle position.See =Idlespeed
adjustment."
• Blade continues to move when the engine idles. See "Idle
speed adjustment."
• Engine dies or hesitates when it should accelerate. See
"Acceleration check?"
° Loss of cuttingpow, e r which cannot be corrected by cleaning
the air filter. See High speed adjustment. "
NOTE.-Do not attempt to turn the adjustments beyond the stops
as damage can occur.
CARBURETOR PRESETS (Fig. 16)
The carburetor has three adjustingscrews:
L = Low speed mixture adjusting screw
H = High speed mixture adjustingscrew
T = Idle speed adjusl_ng screw
If your engine will not start due to suspectedimpropercarbure-
tor adjustment, the following presets may be required. If used, it
is recommended that all steps w;thin the adjustment procedure
be completed in order at assure a properly set carburetor If pre-
sets are not needed, proceed to section =Idlespeed adjustment."
Very small adjustments can affect engine performance. It is
important to tum the screw a very small amount per adjustment
and test performance before making further adjustments. Each
ADJUSTING PROCEDURE
IDLE SPEED ADJUSTMENT
Allowthe warm engineto idle.
Adjustthe idlespeed screwuntilthe engine continuesto run
withoutstallingandwithoutthe bladeturning.
- Turnscrewclockwise toincreaseengine speedif enginestalls
or dies.
- Turnscrew counterclockwise to stow engine down and/or to
keep the blade from turning.
• No further adjustments are necessary if blade does not move
at idlespeed and if performance is satisfactory.
LOW SPEED ..._,
MIXTURE
ADJUSTMENT
IDLE SPEED
HIGH SPEED
MIXTURE
COVER
Figure 16
LOW SPEED MIXTURE ADJUSTMENT
• Allow engine to idle.
• Turn the low speed mixtureadjustment slowlyclockwiseuntil
the RPM startsto drop.Note the position.
• Turn the low speed adjustment slowlycounterclockwise u ntil
the RPM speedsupand startsto dropagain.Notetheposition.
• Set the low speed mixturescrewat the midpoint betweenthe
twopositions.
HIGH SPEED MIXTURE ADJUSTMENT
IMPORTANT:DONOT OPERATEENGINE AT FULLTHROTTLE
FOR PROLONGED PERIODS WHILE MAKING HIGH SPEED
ADJUSTMENTSAS DAMAGETOTHE ENGINE CAN OCCUR.
• Make a test cuL
• Based on performanceof the unit while cutting,adjust the
high speed mixture adjustment in 1/16 turn increments as fol-
lows:
- Clockwise if unitsmokes or loses power while cutting. Do not
adjustfor best power by sound or speed, but judge by how
well the unitperforms duringoperation.
- Counterclockwise if the unit has speed while not cutting,but
dies or lackspower while curing.
• Repeatthe test cut.
• Continue w_ 1/16 turn adjustments until the unit perfor-
mance is acceptablewhilecutting.
• After completing adjustments, check for aoceleralJon.
• If unit accelerates properly no further adjustments are neces-
sary. If not, proceed to acceleration check.
ACCELERATION CHECK
• ff the enginedies or hesitatesinsteadof accelerating, turn the
low speed mixture adjustment1/16 of a turn at a time coun-
terclockwise untilyou have smooth acceleration.
• Check the idle speedfor stability and that the blade does not
turn.Adjustas necessary.
• Recheckfor smooth acceleration and stable idle,
• Repeat process as necessary for acceptable performance.
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