Carburettor - Adjustment - Husqvarna 340 Workshop Manual

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, altitude,
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
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.
!
WARNING!
The guide bar, chain and clutch
cover must be fitted before the
saw is started, otherwise the
clutch may fly off and cause injury.
36
– English
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 recommended
maximum speed.
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 finally the H jet screw.
The recommended engine speeds are as follows:
Model Max. speed
340 12,500 rpm
345 12,500 rpm
346 XP/G 14,700 rpm
350 13,000 rpm
351 /G 13,000 rpm
Idling speed
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm