Maintenance; Carburettor; Muffler - Husqvarna 240F Operator's Manual

Carburettor

Your Husqvarna product has been designed and
manufactured to specifications that reduce harmful
emissions. After the engine has used 8-10 tanks of fuel the
engine will be run-in. To ensure that it continues to run at peak
performance and to minimise harmful exhaust emissions
after the running-in period, ask your dealer/service workshop
(who will have a rev counter at their disposal) to adjust your
carburettor.
Function
• The carburettor governs the engine's speed via the
throttle control. Air and fuel are mixed in the carburettor.
The air/fuel mixture is adjustable. Correct adjustment is
essential to get the best performance from the machine.
• Adjusting the carburettor means that the engine is
adapted to local operating conditions, e.g. climate,
altitude, petrol and the type of 2-stroke oil.
• The carburettor has three adjustment controls:
L = Low speed jet
H = High speed jet
T = Idle adjustment screw
• The L and H-jets are used to adjust the supply of fuel to
match the rate that air is admitted, which is controlled with
the throttle. If they are screwed clockwise the air/fuel ratio
becomes leaner (less fuel) and if they are turned anti-
clockwise the ratio becomes richer (more fuel). A lean
mixture gives a higher engine speed and a rich mixture
gives a lower engine speed.
• The T-screw regulates the throttle setting at idle speed. If
the T-screw is turned clockwise this gives a higher idle
speed; turning it anti-clockwise gives a lower idle speed.

MAINTENANCE

Basic setting
• The basic carburettor settings are adjusted during testing
at the factory. The basic setting is richer than the optimal
setting and should be maintained for the first few hours the
machine is in use. The carburettor should then be finely
adjusted. Fine adjustment should be carried out by a
skilled technician.
The basic setting can vary between: H = 1 - 1 1/4 turns
and L = 1 - 1 1/4 turns.
CAUTION! If the cutting attachment rotates when the engine
is idling the idle adjustment screw T should be turned anti-
clockwise until the cutting attachment stops.
240R, 240F, 250R, 252RX:
Rec. idle speed 2700 rpm
265RX:
Rec. idle speed 2250 rpm
!
CAUTION! The machine should only be run for short periods
at its highest speed. For optimum adjustment of the
carburettor, contact a qualified dealer/service workshop that
has a revolution counter at their disposal.
Recommended max. speed: See the Technical data section.
During the running-in period (8-10 tanks of fuel) the maximum
speed should be set 600-700 rpm below the recommended
maximum speed (= open the high speed jet H a further 1/8
turn).
Muffler
CAUTION! Some mufflers are fitted with a catalytic converter.
See chapter on Technical data to see whether your machine
is fitted with a catalytic converter.
The muffler is designed to reduce the noise level and to direct
the exhaust gases away from the operator. The exhaust
gases are hot and can contain sparks, which may cause fire
if directed against dry and combustible material. Some
mufflers are equipped with a special spark arrestor mesh. If
your machine has this type of muffler, you should clean the
mesh at least once a week. This is best done with a wire
brush. On mufflers without a catalytic converter the mesh
should be cleaned weekly, or replaced if necessary. On
mufflers fitted with a catalytic converter the mesh should be
checked, and if necessary cleaned, monthly. If the mesh is
damaged it should be replaced.
WARNING! If the idle speed cannot be
adjusted so that the cutting attachment
stops, contact your dealer/service
workshop. Do not use the machine until it
has been correctly adjusted or repaired.
– 29
English