Husqvarna ST724 - Manual (Page 26)

27
SERVICE AND ADJUSTMENTS
TO ADJUST OR REPLACE THE SPARK
PLUG
If you have difficulty starting your snow thrower, you may
need to adjust or replace the spark plug. Follow the
instructions below.
Replace the spark plug if the electrodes are pitted or
burned or if the porcelain is cracked.
TO ADJUST:
● Clean the spark plug by carefully scraping the
electrodes (do not sand blast or use a wire brush).
● Be sure the spark plug is clean and free of foreign
material. Check the electrodes gap (See III.34) with
a wire feeler gauge and reset the gap to .030 inch if
necessary.
TO REPLACE:
● Remove the spark plug wire.
● Clean the area around the plug base to prevent dirt
from entering the engine when the plug is removed.
● Remove the spark plug. If it is cracked, fouled or
dirty, it must be replaced.
● Set the gap between the electrodes of the new spark
plug at .030 inch. Next, install the spark plug in the
cylinder head. Tighten the plug to 18 to 23 foot
pounds. If you do not use a torque wrench, tighten
the plug firmly (See III.34).
TO ADJUST CARBURETOR
The carburetor (See III.33) has been pre-set at the
factory and readjustment should not be necessary. How-
ever, if the carburetor does need to be adjusted, proceed
as follows:
● Close the high speed adjusting screw by hand.
● Do not over tighten.
● Then open it 1-1/4 to 1-1/2 turns.
● Close the idle adjusting screw by turning clockwise
by hand. Do not over tighten.
● Then open it 1-1/4 to 1-1/2 turns.
● Start the engine and let it warm up.
● Set the throttle control to RUN. Adjust the high speed
adjusting screw in until the engine speed or sound
alters. Adjust the screw out until the engine speed
sound alters. Note the difference between the two
limits and set the screw in the middle of the range.
● Let the engine run undisturbed for 30 seconds after
each setting to allow the engine to react to the
previous adjustment.
● Set the throttle control to SLOW. Adjust the idle
adjusting screw in until the engine speed drops, then
adjust the screw out until the engine speed drops.
Note the difference between the two limits and set
the screw in the middle of the range.
● If the engine tends to stall under load or does not
accelerate from low speed to high speed properly,
adjust the high speed screw out in 1/8 turn incre-
ments until the problem is resolved. Let the engine
run for 30 seconds between settings.
IMPORTANT: NEVER TAMPER WITH THE ENGINE
GOVERNOR, WHICH IS FACTORY
SET FORPROPER ENGINE SPEED.
OVER-SPEEDING THE ENGINE
ABOVE THE FACTORY HIGH SPEED
SETTING CAN BE DANGEROUS. IF
YOU THINK THE ENGINE -GOV-
ERNED HIGH SPEED NEEDS AD-
JUSTING, CONTACT YOUR NEAR-
EST AUTHORIZED SERVICE CEN-
TER, WHICH HAS THE PROPER
EQUIPMENT AND EXPERIENCE TO
MAKE ANY
NECESSARY ADJUSTMENTS. A
DISTRIBUTOR'S LIST IS ON THE
INSIDE BACK COVER OF THIS
MANUAL.