Jonsered CS 2171 - Manual (Page 31)

English – 31
MAINTENANCE
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.
• 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.
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 anticlockwise 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.
High speed jet H
• The high speed jet H influences the power and engine
speed of the machine. If the high speed jet is set too rich
(H-jet screwed in too far) the machine will over-rev and this
will damage the engine. Run the machine at full throttle for
about 10 seconds. Then turn the H-jet 1/4 turn anti-
clockwise. Run the machine at full throttle for another 10
seconds or so and listen to the difference in the fast idle
speed. Repeat this procedure with the H-jet turned a
further 1/4 turn anti-clockwise.
• You have now run the machine at settings of H = ±0, H=+1/
4, H=+1/2 relative to the basic settings. At full throttle the
engine has sounded different for each setting. The H-jet is
correctly adjusted when the machine burbles a little. If the
machine ”screams” then the machine is set too lean. If the
muffler emits a lot of smoke and the machine burbles a lot
then the setting is too rich. Turn the H-jet clockwise until
the setting sounds right
CAUTION! To ensure correct adjustment you should enlist a
qualified mechanic who has access to a tachometer. The
recommended maximum fast idle speed must not be
exceeded.
Correctly adjusted carburettor
When the carburettor is correctly adjusted the machine
accelerates without hesitation and 4-cycles a little at full
throttle. It is also important that the chain does not rotate at
idle. If the L-jet is set too lean it may cause starting difficulties
and poor acceleration. If the H-jet is set too lean the machine
will have less power, poor acceleration and could suffer
damage to the engine.
If both the L and H jets are set too rich it will results in
acceleration problems or too low a working speed.
Checking, maintaining and servicing
chain saw safety equipment
Chain brake and front hand guard
Checking brake band wear
Brush off any wood dust, resin and dirt from the chain brake
and clutch drum. Dirt and wear can impair operation of the
brake.
Regularly check that the brake band is at least 0.6 mm thick
at its thinnest point.
!
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
H
Note! All service and repair work on the machine demands
special training. This is especially true of the machine’s
safety equipment. If your machine fails any of the checks
described below we recommend that you take it to your
service workshop.