MAINTENANCE
English – 31
Function
• The carburettor governs the engine’s speed via the
throttle control. Air and fuel are mixed in the
carburettor. The air/fuel mixture is adjustable. Correct
adjustment is essential to get the best performance
from the machine.
• Adjusting the carburettor means that the engine is
adapted to local operating conditions, e.g. climate,
altitude, petrol and the type of 2-stroke oil.
• The carburettor has three adjustment controls:
- L = Low speed jet
- H = High speed jet
- T = Idle adjustment screw
• 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 carburettor settings are adjusted during testing
at the factory. The basic settings are H = 1 turn and L =
1 turn. To provide the engine’s components with good
initial lubrication (during running in) the carburettor should
be set for a richer fuel mixture for the first 3-4 hours that
the chain saw is in use. To do this, adjust the fast idle
speed to 600-700 rpm below the recommended maximum
fast idle speed.
If you are unable to check the fast idle speed using a
tachometer the H-jet should not be set for a leaner mixture
than given in the basic settings. The recommended
maximum fast idle speed must not be exceeded.
CAUTION! If the chain rotates while idling the T-screw
must be turned anti-clockwise until the chain stops.
Fine adjustment
When the machine has been ”run-in” the carburettor
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.
The recommended engine speeds are as follows:
Conditions
•Before any adjustments are made the air filter should
be clean and the cylinder cover fitted. Adjusting the
carburettor 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 the L and H-jets clockwise as far as they
will go. Now turn the jets one turn anti-clockwise. The
carburettor is now set to H = 1 and L = 1.
• 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
Try to find the highest idle speed by turning the low speed
jet L clockwise then anti-clockwise. When the highest
speed has been found, turn the low speed jet L 1/4 turn
anti-clockwise.
CAUTION! If the chain rotates while idling the T-screw
must be turned anti-clockwise until the chain stops.
Fine adjustment of the idle speed T
Adjust the idle speed using the idle adjustment screw T, if
it is necessary to readjust. First turn the idle adjustment
screw T clockwise until the cutting attachment starts to
rotate. Then turn the screw counter clockwise until the
cutting attachment stops. The idle speed is correctly
adjusted when the engine will run smoothly in every
position. The idle speed should also be well below the
speed at which the cutting attachment starts to rotate.
!
WARNING! Contact your servicing
dealer, if the idle speed setting cannot be
adjusted so that the chain stops. Do not
use the chain saw until it has been
properly adjusted or repaired.
L
+ 1/4