Carburettor Setting - Husqvarna 322 Workshop Manual

L
H
L
H
Fuel system

Carburettor setting

!
WARNING!
The clutch and clutch cover must, under all circumstances, be fitted
when testing running the engine after adjusting the carburettor.
Otherwise there is a risk that the clutch can become loose and cause
serious personal injury.
Function
The carburettor has the task of delivering a combustible air/fuel mixture to the
cylinder.
The amount of mixture is controlled by the throttle.
The mixture's composition of petrol and air is controlled by using the adjustable
needles "H" and "L".
The needles must be correctly adjusted so that the engine can give maximum
power at different speeds, run smoothly when idling and react quickly when acceler-
ating.
The carburettor setting can vary a little depending on the humidity, temperature and
air pressure.
L = Low speed needle
H = High speed needle
T = Idle speed adjuster screw
The fuel quantity in relation to the air flow permitted by the throttle opening is
adjusted by the L and H needles. Turning the needles clockwise gives a leaner
fuel mixture (less fuel) and turning them anticlockwise gives a richer fuel mixture
(more fuel). A leaner mixture gives higher revs while a richer mixture gives less
revs.
The T-screw regulates the position of the throttle while the engine is idling.
Turning the screw clockwise gives a higher idling speed while turning it anti-
clockwise gives a lower idling speed.
Basic setting
The carburettor is set to its basic setting when test run at the factory. The basic
setting is "richer" than the optimal setting (the max speed is 600–800 r/min under
the recommended max. speed) and should be kept during the engine's first working
hours. Thereafter the carburettor should be finely adjusted.
Some carburettors are fitted with plastic sleeves with a limiter, so-called CARB- and
EPA-versions for USA. This type of carburettor can also be found on other markets
for certain models. When making carburettor adjustments as set out below the
adjustment range for the H and L needles can be too small. In such cases the
plastic sleeves must be removed (using pliers) in order for satisfactory adjustment
to be made.
Fine adjustment
Fine adjustment of the carburettor should be carried out after the engine has been
"run-in".
The air filter should be clean and the cylinder cover fitted when adjustments are
made.
First adjust the L needle, then the H needle and finally the idling speed's T-
screw.
The following speed recommendations apply:
Idling speed = 2 500 r/min.
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