Carburettor Adjustment - Husqvarna 390XP Workshop Manual

Carburettor

14.9 Carburettor adjustment

WARNING!
The guide bar, saw chain and clutch
cover must be fitted before the chain saw
is started, or the clutch can come loose
causing personal injury.
WARNING!
Wear ear protection when making
adjustments with the engine running.
WARNING!
Do not use the chainsaw until it has been
adjusted so that the saw chain is still
during idling.
NOTE! For optimal setting, a tachometer should
be used. The recommended maximum over-speed
should not be exceeded.
NOTE! If the saw chain turns when idling, the
T-screw should be turned anti-clockwise until the
saw chain stops.
Adjusting the carburettor involves adjusting the engine
to the local conditions for example climate, altitude, fuel
and type of 2-stroke oil.
The carburettor is equipped with three adjustment op-
tions:
• L = Low speed jet
• H = High speed jet
• T = Idling adjustment
The L- and H-jets adjust the fuel flow to match the air-
flow that the throttle valve opening allows. Turning them
clockwise makes the fuel and air mixture weaker (less
fuel) and turning them counter-clockwise makes the fuel
and air mixture richer (more fuel). A weaker mixture in-
creases 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 counterclockwise gives lower idling speed.
Run the chain saw for approx. 10 minutes before adjust-
ing the carburettor.
38 - English