Husqvarna 334T Workshop Manual page 40

For Husqvarna Parts Call 606-678-9623 or 606-561-4983
Carburettor
Your Husqvarna product has been designed and manufactured
according to specifications that reduce harmful gases.
When you engine has consumed 8-10 tanks of fuel the engine
has been "run-in". To ensure that it runs in the best possible
way and emits as few harmful gases as possible after the
running in period, let your dealer/service workshop that has a
tachometer, adjust your carburettor so that it gives optimal
performance.
Function, Basic setting, Fine tuning
WARNING! The bar, chain and clutch cover
(chain brake) must be fitted before the saw is
started otherwise the clutch can work loose
and cause personal injury.
Function
• The carburettor controls the speed of the engine via the
throttle. Air/fuel is mixed in the carburettor. This air/fuel
mixture is adjustable. The adjustment must be correct to utilise
the saw's maximum power.
• Adjustment of the carburettor means that the engine is
adapted to local conditions, e.g. the climate, altitude, petrol
and the type of 2-stroke oil.
• The carburettor is fitted with
three adjustment possibilities:
L = Low speed needle
H = High speed needle
T = Adjuster screw for idling
• The fuel quantity in relation to the air flow permitted by the
throttle opening is adjusted by the L and H-needles. Turning
the needles clockwise gives a leaner fuel mixture (less fuel)
and turning them anticlockwise gives a richer fuel mixture
(more fuel). A lean mixture gives a higher speed while a richer
mixture gives a lower speed.
• The T-screw regulates the position of the throttle while the engine
is idling. Turning the screw clockwise gives a higher idling speed
while turning it anticlockwise gives a lower idling speed.
Basic setting and running-in
The carburettor is set to its basic setting when test run at the
factory. The basic setting is richer than the optimal setting and
should be kept during the engine's first working hours. Thereaf-
ter the carburettor should be fine tuned. Fine tuning should be
done by a qualified mechanic.
NOTE! If the chain rotates while idling the T-screw should be
turned anticlockwise until it stops.
Recommended idling speed: 2,800 rpm
WARNING! Contact your service workshop if
the idling speed cannot be adjusted so that
the chain does not rotate. Do not use the saw
until it is adjusted correctly or repaired.
Fine adjustment
• Fine adjustment of the carburettor should be carried out once
the engine has been "run-in". Fine tuning should be done by
a qualified mechanic. First adjust the L-needle, then the
idling speed's T-screw and finally the H-needle.
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CARBURETTOR
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Conditions
• The air filter should be clean and the carburettor cover fitted
when adjustments are made. Adjusting the carburettor with a
dirty air filter will give a too lean fuel mixture the next time the
air filter is cleaned. This can result in serious damage to the
engine.
• Carefully turn the L and H-needles to the centre position
between fully screwed in and fully screwed out.
• Do not attempt to adjust the needles past the stop, as this
can result in damage.
• Start the saw according to the start instruction and run warm
for 10 minutes.
NOTE! If the chain rotates while idling the T-screw should
be turned anticlockwise until it stops.
• Place the saw on a flat surface so that the bar points away
from you and so that the chain and bar do not make contact
with the surface or any other objects.
Low speed needle L
Screw the L-needle clockwise until it stops. If the engine has
bad acceleration or uneven idling turn the L-needle anti-
clockwise until good acceleration and idling are obtained.
NOTE! If the chain rotates while idling the T-screw should
be turned anticlockwise until it stops.
Fine tuning idling T
Adjustment of the idling speed is done with the screw marked T.
If adjustment is necessary, screw in (clockwise) the idling screw
T with the engine running until the chain starts to rotate. Now
open (anticlockwise) until the chain is at a standstill. A correctly
set idling speed is when the engine runs smoothly in all positions
with a good margin to the speed when the chain starts to rotate.
WARNING! Contact your service workshop if
the idling speed cannot be adjusted so that
the chain does not rotate. Do not use the saw
until it is adjusted correctly or repaired.
High speed needle H
The high speed needle H
affects the saw's power and
speed. A too lean high speed
needle setting (H-needle
screwed in too far) gives over
revving on the saw resulting in
damage to the engine. Turn the
H-needle anticlockwise until it
stops. If the engine runs
unevenly turn the H-needle
clockwise until the engine
xruns evenly.
The H-needle is set correctly when the saw "splatters" a little. If
the saw "screams" the setting is too lean. If the muffler smokes
heavily, at the same time as the saw splatters a great deal the
setting is too rich. Turn the H-needle clockwise until you find the
setting that sounds right.
NOTE! Use a mechanic with access to a tachometer to
make an optimal setting.
Correctly adjusted carburettor
A correctly adjusted carburettor means that the saw accelerates
without hesitation and that it 4-strokes a little at full throttle. In
addition the chain should not rotate when idling. An L-needle
adjusted too lean can cause starting difficulties and bad accel-
eration. An H-needle adjusted too lean gives the saw lower
power = "less strength", bad acceleration and/or damage to the
engine. A too rich setting of the L and H-needles gives accel-
eration problems or a too low working speed.
H