Husqvarna 268K, 272K manual Carburettor

MAINTENANCE

Carburettor

Operation, Basic settings, Fine tuning

!WARNING! The power cutter must be correctly assembled with cutting arm and cutting head before you start (See chapter ” Assembly”.)

Operation

•The carburettor governs the engine‘s speed via the throttle. Air/fuel is mixed in the carburettor. The air/fuel mixture is adjustable. To take advantage of the engine‘s optimal output the adjustment must be correct.

•The setting of the carburettor means that the engine is adapted to local conditions, for example, the climate, altitude, petrol and the type of 2-stroke oil.

T

L H

• The carburettor is equipped

with three adjustment

possibilities:

L = Low speed needle

H = High speed needle

T = Idle speed adjuster

Fine tuning

•When the machine has been run-in the carburettor is finely tuned. Fine tuning should be carried out by trained personnel. The L-needle is adjusted first, then the idling screw T and finally the H-needle. The following speed recommendations apply:

Max. speed Idling speed

10,000 rpm 2,500 rpm

Conditions

•The air filter should be clean and the cylinder cover fitted when all adjustments are made. If the carburettor is adjusted with a dirty air filter a too lean fuel mixture is obtained the next time the air filter is cleaned. This can result in serious damage to the engine.

•Carefully screw (clockwise) the L and H needles until they bottom. Then screw out (anti-clockwise) the needles one turn. The carburettor now has the setting H = 1 and L = 1.

•Start the power cutter as set out in the start instructions (see section ”Start and stop”) and run the cutter warm for 10 minutes. NOTE! If the cutting disc rotates while the engine is idling the T-screw should be turned anti-clockwise until the cutting disc stops.

screw

• The fuel quantity in relation to the air flow permitted by the

throttle opening is adjusted using the L and H-needles.

Turning the needles clockwise gives a leaner fuel mixture

(less fuel) and turning them anti-clockwise gives a richer fuel

Low speed needle L

• Find the highest idling speed by slowly screwing the low speed needle clockwise respective anti- clockwise. When the highest speed is found,

+ 1/4

mixture (more fuel). A leaner mixture gives high revs while a

richer mixture give 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 H = 3/4 turn respective L = 1 turn.

The carburettor should be set for a richer fuel mixture during the first 3–4 hours of use so that the engine parts are given good initial lubrication (running-in). To set this, adjust the maximum speed to 6-700 rpm under the recommended maximum speed.

If you do not have the possibility of checking the maximum speed with a tachometer, the H-needle must not be set for a leaner mixture than stated for the basic settings.

The recommended maximum speed must not be exceeded.

NOTE! If the cutting disc rotates while the engine is idling the T- screw should be turned anti-clockwise until the cutting disc stops.

screw the L-needle 1/4 turn L anti-clockwise. NOTE! If the

cutting disc rotates while the engine is idling the T-screw should be turned anti- clockwise until the cutting disc stops.

Fine tuning idling T

Idling is set using the screw marked T. If adjustment is necessary screw in (clockwise) the idling screw T with the engine running until the cutting disc starts to rotate. Thereafter open (anti-clockwise) until the disc stops rotating. The correct idling speed is set when the engine runs smoothly in all positions with a good margin to the speed when the disc starts to rotate.

!WARNING! If the idling speed cannot be adjusted so that the disc stops, contact your service workshop. Do not use the machine until it has been correctly adjusted or repai- red.

English – 17