Jonsered CS 2141 Workshop Manual page 43

If it is not possible to check the maximum speed
with a tachometer then the H jet should not be set
to a weaker mixture than the basic factory setting.
The recommended maximum speed must not
be exceeded.
NOTE!
If the chain turns at idling speed, the T
screw should be turned anti-clockwise
until the chain stops.
Fine adjustment
Once the chainsaw is "run in" the carburettor
should be readjusted. First adjust the L jet screw,
then the idling screw T and fi nally the H jet screw.
The recommended engine speeds are as follows:
Model Max revs
CS 2141 12,500 rpm
CS 2145 12,500 rpm
CS 2147 14,200 rpm
CS 2149 13,000 rpm
CS 2150 13,000 rpm
CS 2152 13,000 rpm
CS 2156 14,000 rpm
CS 2159 13,500 rpm
Basic requirements
• Before making any adjustments the air fi lter
should be clean and the cylinder cover should
be in place. If the carburettor is adjusted with a
dirty air fi lter, the mixture will be too weak next
time the air fi lter is cleaned. This can cause seri-
ous engine damage.
• Carefully screw in the L and H jets fully, then
back them off 1 turn. The carburettor now has
the settings H = 1 and L = 1.
• Start the chainsaw and allow it to warm up for
10 minutes.
• Place the saw on a fl at surface so that the guide
bar is pointing away from you and the guide bar
and chain are not touching the surface.
Low speed jet L
• Find the highest idling speed by slowly screwing
the L screw in and then out again.
• When the highest speed has been found, screw
out the L screw 1/8 - 1/4 turn.
Fine adjustment of idling speed T
• The idling speed is adjusted using the screw
• If adjustment is necessary, screw in the idling
• The idling speed is correctly set when the engine
High speed jet H
• The high speed jet H infl uences the saw power
• Run the saw at full throttle for about 10 seconds.
Idle revs • Then screw out the H screw 1/4 turn. H=1 1/4.
2,700 rpm
• Run the saw again at full throttle for about 10
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm
• You have now run the saw at settings H ± 0, H =
2,700 rpm
2,700 rpm
2,700 rpm
• The H screw is correctly adjusted when the saw
• If there is a lot of smoke from the silencer and the
• Screw in the H screw to the setting that sounds
Carburettor – correct adjustment
• When the carburettor is correctly adjusted the
• The chain must not turn when idling.
• If the L screw is set too weak this can make the
• If the H screw is set too weak the saw will produce
• If either the L or H screws are set too rich it will
marked T.
screw T until the chain starts to turn. Then screw it
out until the chain stops moving.
runs smoothly in all positions and there is a clear
margin to the speed at which the chain starts to
move.
output and engine speed. If the H jet is set too
weak the saw will over-rev, which could cause
engine damage.
H=1.
seconds and listen to the difference in the engine
note. Repeat this procedure again with the H
screw screwed out another 1/4 turn. H=1 1/2.
+1/4 and H = +1/2 from the factory setting. At full
throttle the engine will sound different at each set-
ting.
"burbles" a little at full throttle without any load.
saw does not run smoothly then the setting is too
rich.
right.
NOTE!
For optimum adjustment, a tachometer
should be used. The recommended maxi-
mum speed should not be exceeded.
saw should accelerate without hesitation and the
engine will burble a little at full throttle without any
load.
saw diffi cult to start and cause poor acceleration.
less power, poor acceleration and there is a risk of
engine damage.
cause acceleration problems or too low working
speed.
Repair instructions
43
English –