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Repair instructions
Carburettor – adjustment
For instructions on adjusting the EPA carburettor
see appendix A.
Adjusting the carburettor involves adjusting the
engine to the local conditions e.g. climate, alti-
tude, fuel and type of two-stroke oil.
The carburettor is equipped with three adjustment
options.
L = Low speed jet
H = High speed jet
T = Idling adjustment screw
WARNING!
The guide bar, chain and clutch
cover must be fitted before the
saw is started, otherwise the
clutch may fly off and cause inju-
ry.
The L and H jets adjust the fuel flow to match the
airflow that the throttle valve opening allows.
Turning them clockwise makes the fuel/air mixture
weaker (less fuel in relation to the amount of air)
and turning them anti-clockwise makes the fuel/air
mixture richer. A weak mixture increases the
engine speed and a rich mixture decreases the
engine speed.
The T screw controls the throttle position when
idling. Turning the T screw clockwise gives faster
idling; turning it anti-clockwise lowers idling
speed.
Basic settings and running in
During testing at the factory the carburettor is
adjusted to the basic factory settings.
The factory settings are H = 1 turn and L = 1
turn.
To ensure that engine components receive
adequate lubrication (running in) the carburet-
tor should be set to a somewhat richer fuel
mixture for the chainsaw’s first 3-4 running
hours. This is done by adjusting the maximum
speed to 6-700 rpm less than the recom-
mended maximum speed.
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 finally the H jet screw.
The recommended engine speeds are as follows:
Model Max revs Idle revs
340 12,500 rpm 2,700 rpm
345 12,500 rpm 2,700 rpm
346XP/G 14,200 rpm 2,700 rpm
350 13,000 rpm 2,700 rpm
350 EPA 13,000 rpm 2,700 rpm
351 13,000 rpm 2,700 rpm
353 13,000 rpm 2,700 rpm
NOTE!
If the chain turns at idling speed, the T
screw should be turned anti-clockwise
until the chain stops.
Basic requirements
• Before making any adjustments the air filter
should be clean and the cylinder cover should be
in place. If the carburettor is adjusted with a dirty
air filter, the mixture will be too weak next time
the air filter is cleaned. This can cause serious
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 flat 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.
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.