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Carburetor
Your Husqvarna product has been designed and
manufactured to specifications that reduce harmful
emissions. After the engine has used 8-10 tanks of fuel
the engine will be run-in. To ensure that it continues to run
at peak performance and to minimise harmful exhaust
emissions after the running-in period, ask your dealer/
service workshop (who will have a rev counter at their
disposal) to adjust your carburettor.
Function, Basic settings, Fine adjustment
WARNING! Do not start the chain saw
!
unless the bar, chain and clutch cover
(chain brake) are fitted, otherwise the
clutch may come loose and cause
personal injury.
Function
•
The carburetor governs the engine's speed via the
throttle control. Air and fuel are mixed in the carburetor.
The air/fuel mixture is adjustable. Correct adjustment is
essential to get the best performance from the machine.
•
The setting of the carburetor means that the engine is
adapted to local conditions, for example, the climate,
altitude, fuel and the type of 2-stroke oil.
•
The carburetor has three adjustment controls:
- L = Low speed jet
- H = High speed jet
- T = Idle adjustment screw
H
•
The L and H-jets are used to adjust the supply of fuel
to match the rate that air is admitted, which is
controlled with the throttle. If they are screwed
clockwise the air/fuel ratio becomes leaner (less fuel)
and if they are turned anti-clockwise the ratio becomes
richer (more fuel). A lean mixture gives a higher engine
speed and a rich mixture gives a lower engine speed.
•
The T-screw regulates the throttle setting at idle speed.
If the T-screw is turned clockwise this gives a higher idle
speed; turning it anti-clockwise gives a lower idle speed.
Basic settings and running in
The basic carburetor settings are adjusted during testing
at the factory. The basic setting is richer than the optimal
setting and should be maintained for the first few hours
the machine is in use. The carburettor should then be
finely adjusted. Fine adjustment should be carried out by
a skilled technician.
CAUTION! If the chain rotates while idling the T-screw
must be turned anti-clockwise until the chain stops.
Rec. idle speed: 2800 rpm
MAINTENANCE
L
T
Fine adjustment
When the machine has been "run-in" the carburetor
should be finely adjusted. The fine adjustment should
be carried out by a qualified person. First adjust the L-
jet, then the idling screw T and then the H-jet.
Fine tuning may be required if the chain saw, after
changing the type of fuel, performs differently with regard
to starting, acceleration, maximum speed, etc.
Conditions
•
Before any adjustments are made the air filter should
be clean and the cylinder cover fitted. Adjusting the
carburetor while a dirty air filter is in use will result in a
leaner mixture next time the filter is cleaned. This can
give rise to serious engine damage.
•
Carefully turn both jets, L and H, so that they are
midway between fully screwed in and fully screwed
out.
•
Do not attempt to adjust the L and H jets beyond
either stop as this could cause damage.
•
Now start the machine according to the starting
instructions and let it warm up for 10 minutes.
CAUTION! If the chain rotates while idling the T-
screw must be turned anti-clockwise until the
chain stops.
•
Place the machine on a flat surface so that the bar
points away from you and so that the bar and chain do
not come into contact with the surface or other
objects.
Low speed jet L
Turn the low speed jet L clockwise until it stops. If the
engine accelerates poorly or idles unevenly, turn the low
speed jet L anticlockwise until good acceleration and
idling are achieved.
CAUTION! If the chain rotates while idling the T-screw
must be turned anti-clockwise until the chain stops.
Fine adjustment of the idling speed T
Final setting of the idling speed T
Adjust the idle speed with the T-screw. If it is necessary to
re-adjust, turn the T-screw clockwise while the engine is
running, until the chain starts to rotate. Then turn counter-
clockwise until the chain stops. A correctly adjusted idle
speed setting occurs when the engine runs smoothly in
every position. It should also be good margin to the rpm
when the chain starts to rotate.
WARNING! Contact your servicing
!
dealer, if the idle speed setting cannot be
adjusted so that the chain stops at idle.
Do not use the chain saw until it has
been properly adjusted or repaired.
–
English
29
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