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E. Carburetor Adjustment
1. General
NOTE: The diaphragm carburetor has three external
adjustments. Each adjustment affects the others.
The idle speed adjustment screw controls the throttle opening
at idle position.
The low (LO) speed adjustment screw controls the volume of
fuel mixture at low engine speed. It also controls the
supplementary fuel required to obtain smooth progression from
idling to high speed.
The high (HI) speed adjustment screw controls the volume of
fuel mixture at full throttle.
2. Carburetor Adjustment
Every unit is run at the factory and the car bu re tor is set in
compliance with EPA California Emis sion Reg u la tions. In
addition, the carburetor is equipped with HI and LO needle
adjustment limiters that prevent settings outside acceptable
limits. Limiter caps must remain or be replaced on both the Hi
and Lo carburetor adjusting screws. There is no limiter cap on
the idle screw.
NOTE: The needle screws have a sharp point. To avoid damage
to the carburetor, do not use excessive force.
a. Before adjusting carburetor clean or replace air filter and
muffler, "Spark Arrestor Screen".
b. Make sure the cutting attachment such as hedge clipper
blades are properly adjusted.
c. Start engine and run several minutes to bring to operating
temperature. Flash choke twice during warm-up to clear any
air from the fuel system.
NOTE: The Idle speed screws may have to be re-adjusted to
keep engine from stalling. The Engine must be at normal
operating temperature to adjust properly.
d. Stop engine. Turn HI speed needle counter-clockwise to stop.
Turn LO speed needle midway between full clockwise stop
and counter-clockwise stop.
e. Idle Speed Adjustment
Units with Cutting Attachments.
Turn "idle" speed adjustment screw CW (clockwise) until
cutting at tach ment begins to turn, then turn screw out
CCW (counter clockwise) until at tach ment stops turning.
Turn screw out, CCW, an additional 1/4 turn.
f. Start unit and accelerate to full throttle for 2-3 seconds to
clear any excess fuel in the engine, then return to idle.
Accelerate engine to full throttle to check for smooth
transition from idle to high speed. If engine hesitates turn
LO needle CCW 1/8 turn and repeat acceleration. Con tin ue
ad just ment until smooth ac cel er a tion results.
g. Check idle speed and reset if necessary as described in “item
e” above. If a tachometer is available idle speed should be
set as specified in the Owner’s Manual.
Important: Do not run the engine at full throttle or with no
load for more than 5-6 seconds to avoid engine damage.
Note: This hedge trimmer is equipped with a speed limiting
carburetor (the high speed circuit has a by-pass system). With
this feature the engine will continue to run even with the high
speed adjusting screw turned all the way in. Although the engine
will continue to run, it will only produce full power with the HI
adjusting screw opened to about 3/8 to 1/2 turn.
F. Notes
HI
LOW
IDLE SCREW
WARNING - DANGER
KEEP HANDS AWAY FROM THE BLADES WHILE
SERVICING THE HEDGE TRIMMER. BE SURE TRIMMER
IS SECURED AND BLADES ARE GUARDED WHILE
MAKING ADJUSTMENTS.
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