Husqvarna 3120XP Maintenance, Carburettor, Function, Basic settings, Fine adjustment, Conditions

MAINTENANCE

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, Basic settings, Fine adjustment

WARNING! Do not start the chain saw unless

!the bar, chain and clutch cover (chain brake) are fitted, otherwise the clutch may come loose and cause personal injury.

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.

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

•The carburettor has two adjustment controls:

-L = Low speed jet

-T = Idle adjustment screw (Maximum speed is controlled by a fixed jet/electronic speed governor).

•The amount of fuel that is mixed with the air admitted by the throttle opening is adjusted using the low speed jet. If this is turned clockwise it gives a leaner air/fuel mixture (less fuel) and if it is turned anti-clockwise it gives a richer air/fuel mixture (more fuel). A leaner mixture gives a higher engine speed, while a richer 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.

Basic settings and running in

The basic carburettor settings are adjusted during testing at the factory. The basic setting is richer than the optimal setting and should be kept during the machine’s first working hours. Thereafter the carburetor should be finely adjusted. Fine adjustment should be carried out by a skilled technician.

NOTE! If the chain rotate while idling the T screw should be adjusted counter-clockwise until it stops.

Recommended idling speed: 2 500 rpm.

Fine adjustment

When the saw has been ”run-in” the carburettor should be finely adjusted. The fine adjustment should be carried out by qualified person. The L-needle is adjusted first, then the idling screw T.

Conditions

•Before any adjustments are made the air filter should be clean and the cylinder cover fitted. Adjusting the carburettor while a dirty air filter is in use will result in a leaner mixture next time the filter is cleaned. This can give rise to serious engine damage.

•Turn the low speed jet carefully clockwise until it bottoms. Now turn it one turn anti-clockwise. The carburettor is now set to L = 1.

•Now start the machine according to the starting instructions and let it warm up for 10 minutes. CAUTION!

If the chain rotates while idling the T-screw must be turned anti-clockwise until the chain stops.

•Place the machine on a flat surface so that the bar points away from you and so that the bar and chain do not come into contact with the surface or other objects.

Low speed jet L

+ 1/4

L

Turn the low speed jet L clockwise until it stops. If the engine accelerates poorly or idles unevenly, turn the low speed jet L anticlockwise until good acceleration and idling are achieved.

CAUTION! If the chain rotates while idling the T-screw must be turned anti-clockwise until the chain stops.

Final setting of the idling speed T

Adjust the idle speed with the T-screw. If it is necessary to re- adjust, turn the T-screw clockwise while the engine is running, until the chain starts to rotate. Then turn counter-clockwise until the chain stops. A correctly adjusted idle speed setting occurs when the engine runs smoothly in every position. It should also be good margin to the rpm when the chain starts to rotate.

WARNING! Contact your servicing dealer, if

!the idle speed setting cannot be adjusted so that the chain stops. Do not use the chain saw until it has been properly adjusted or repaired.

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