Husqvarna 50 Special - Manual (Page 16)

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Carburettor
WARNING! Do not start the saw without the bar, chain and clutch
cover assembled. If you do, the clutch might come loose and
cause severe injuries.
' In the carburettor, air/fuel is mixed. This air/fuel mixture is
adjustable.
' The carburettor has three adjustment possiblities:
L = Low speed needle
H = High speed needle
T = Idle speed adjustment screw
' When the saw is tested at the factory, the carburettor is adjusted
to a basic setting.
• Basic setting;
H=1 turn open, L=1 turn open
Local climate and differences in altitude may require an adjustment.
When working at high altitudes, the H-needle is turned
clockwise, (gives a leaner fuel mixture).
When working at sea level, the H-needle is turned counter­
clockwise, (gives a richer fuel mixture).
NOTEI Small derivations from the basic setting, influence the rpm
of the saw, substantially.
Basic setting of carburettor
Check that the air filter is clean.
Turn the needles H and L carefully in (clockwise) until closed.
Then turn the needles out to the recommended basic position,
(counter-clockwise) H=1 turn open, L=1 turn open.
Start the saw and warm it up, according to the starting instruc­
tions.
idle speed setting
If an adjustment is necessary, adjust with the T screw. Adjust the idle
speed so that the chain does not rotate.
Check the function of the saw, if necessary, make a final
adjustment.
Final setting of carburettor
A final setting of the carburettor can only be done after the basic
setting and when the saw is warmed up.
Apart from minor readjustments, you should leave all car­
burettor settings and repair work to your servicing dealer.
Start with the low speed needle L.
Low speed needle L
Apply full throttle a couple of times and check that the saw is
accelerating without hesitation.
If asetting is necessary, try to reach the maximum idle speed, by
slowly closing the low speed needle L clockwise. Then open
(counter-clockwise), V
4 of a turn.
Check the engine acceleration.
NOTE! A too lean adjusted low speed needle (the L-needle closed
too much), results in starting difficulties. After a correct setting of
the L-needle, you may proceed to setting of the H-needle.
High speed needle H
An adjustment according to local conditions may be done with
the high speed needle.
The high speed needle (H) influences the power of the saw, and
should be adjusted to the basic setting H=1 turn open, the maxi­
mum speed not exceeding 12,500 rpm.
CAUTION! A too lean adjusted high speed needle (the H-needle
turned too far clock-wise) lowers the power of the engine and
causes over-heating. This can result in engine damage.
Final setting of the idling speed T
Adjust the idling speed with the screw marked T.
Corrections to the setting of the idling speed should be done,
after the H and L adjusting screws are correctly adjusted.
If it is necessary to readjust, first turn the idle speed adjusting
screw (T) clockwise, until the chain starts to rotate. Then turn,
counter-clockwise, until the chain stops.
A correctly adjusted idle speed setting (approx. 2,500 rpm)
occurs when the engine runs smoothly In every position. It should
always be good margin to the rpm when the chain starts to rotate.
CAUTION! Contactyourservicingdealer, iftheidlespeedsetting
cannot be adjusted so that the chain stops. Do not use the saw
until it has been properly adjusted or repaired.
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