Carburetor Adjustments; Service And Adjustments - Craftsman 358.797450 Operator's Manual

SERVICE AND ADJUSTMENTS
CARBURETOR ADJUSTMENTS
Carburetor adjustment is critical and if done improp-
erly can permanently damage the engine as well as
the carburetor. Please read all instructions and con-
suit the Troubleshooting section of this manual
before beginning this process. If the engine does not
operate according to these instructions after repeat-
ing the adjusting steps, do not use the unit. For fur-
ther assistance, please call our customer assistance
hotline at 1-800-235-5878.
i_ WARNING:
SERIOUS INJURY TO THE OPERATOR
AND OTHERS CAN OCCUR IF THE CAR-
BURETOR IS NOT PROPERLY ADJUST-
ED. KEEP OTHERS AWAYWHEN MAKING
CARBURETOR ADJUSTMENTS. THE
BLADE SHAFT WILL BE SPINNING DUR-
ING MOST OF THIS PROCEDURE. WEAR
YOUR PROTECTIVE EQUIPMENT AND
OBSERVE ALL SAFETY INSTRUCTIONS.
REMOVE BLADE BEFORE MAKING CAR-
BURETOR ADJUSTMENTS. DO NOT
MAKE ADJUSTMENTS FROM THE BLADE
SIDE OF THE UNIT. HOLD THE UNIT WITH
YOUR HAND.
RECHECK IDLE SPEED AFTER EACH
ADJUSTMENT.THE BLADE SHAFT MUST
NOT TURN AT IDLE SPEED TO AVOID
SERIOUS INJURY TO THE OPERATOR OR
OTHERS.
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. Adjustments may become necessary if
the saw is used at significantly higher altitudes or if you
notice any of the following conditions:
• Engine will not continueto run at idle position. See "Idle
Speed Adiustment" and "Low Speed Mixture
Adjustment."
• Blade continues to spin when engine idfes. See "Idle
Speed Adjustment _.
• Engine dies or hesitates when it should accelerate.See
"Acceleration Adjustment."
• Loss of cutting power whichis not corrected by air filter
cleaning. See "High Speed Mixture Adjustment:
• Engine will not run. See "Trouble Shooting Chart:Then,
if the carburetor requires adjustment, begin with "Basic
carburetor Settings:'
NOTE: There are three adjustments on the carburetor.
• The Idle Speed Adjustment is marked with the letter
"T7
* The two remaining adjustments on the carburetor are
the mixture adjustments. One is marked "L" for low
speed, and the other "H" for high speed.
CARBURETOR PRESETS (Fig. 17)
If your engine will not start d_e to suspected improper
carburetor adjustment, the following presets may be re-
quired. If used, it is recommended that all steps within the
adjustment procedure be completed in order to assure a
properly set carburetor. If presets are not needed, pro-
ceed to section "Idle Speed Adjustment."
When making adjustments, be careful not to force the
ptastic limiter caps beyond the stops or damage will
occur.
Very small adjustments can affect engine performance. It
is importantto make slight adjustments and test perfor-
mance before proceeding. Each adjustment should be no
more than 1/16 of a turn.
• Turn both of the mixture adjustments counterclock-
wise to the stops.
• Turn the idle speed adjustment clockwise until il
stops. Now turn counterclockwise 3 turns.
* if engine fails to start after performing carburetor pre-
sets, 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 "AdjustingProcedure:
ADJUSTING PROCEDURE
IDLE SPEED ADJUSTMENT "T"
• Allow the warm engine to idle.
° Adjust the Idle Speed untilthe engine continues to run
without stallingand without the blade shaft moving.
- Turn clockwise to increase engine speed if engine
stalls or dies.
- Turn counterclockwise to slow engine down and/or to
keep the blade shaft from turning.
• No further adjustments are necessary if blade shaft
does not move at idle speed and if performance is sat-
isfactory.
ACCELERATION CHECK
• If the engine dies or hesitates instead of accelerating,
turn the Low Speed Mixture Adjustment 1/16 of a turn
at a time counterclockwise until you have smooth accel-
eration.
* Check the idle speed for stability and no blade move-
ment. Adjust as necessary.
-Recheck for smooth acceeration and stable idle.
Repeat process as necessary for acceptable perfor*
mance.
LOW SPEED MIXTURE ADJUSTMENT "L"
• Allow engine to idle.
• Turn the Low Speed Mixture Adjustment slowly clock-
wise until the RPM starts to drop. Note the position.
, Turn the Low Speed Mixture Adjustment slowly coun-
terclockwise until the RPM speeds up and starts to
drop again. Note the position.
• Set the Low Speed Mixture at the midpoint between the
two positions.
Readjust idle speed. See _ldle Speed Adjustment:
-" Repeat Acceleration Check for acceptable performance.
-16-