Maintenance, General, Carburettor adjustment

MAINTENANCE

General

The user must only carry out the maintenance and service work described in this manual.

IMPORTANT! Any maintenance other than that described in this manual must be carried out by your servicing dealer (retailer).

Carburettor adjustment

Due to existing environmental and emissions legislation your chain saw is equipped with movement limiters on the carburettor adjuster screws. These limit the adjustment possibilities to a maximum of a 1/2 turn.

1/2

Your Husqvarna product has been designed and manufactured to speciﬁcations that reduce harmful emissions.

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 satisfactory operation of a catalytic converter depends, among other factors, on the correct adjustment of the carburettor. Carefully follow the instructions below, using a tachometer as an aid.

•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.

Basic settings and running in

The basic carburettor settings are adjusted during testing at the factory. Avoid running at a too high speed for extended periods during the ﬁrst 10 hours.

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

Rec. idle speed: 2700 rpm

Fine adjustment

When the machine has been ”run-in” the carburettor should be ﬁnely adjusted. The ﬁne adjustment should be carried out by a qualiﬁed person. First adjust the L-jet, then the idling screw T and then the H-jet.

Changing the type of fuel

Fine tuning may be required if the chain saw, after changing the type of fuel, performs differently with regard to starting, acceleration, maximum speed, etc.

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.

•Do not attempt to adjust the L and H jets beyond either stop as this could cause damage.

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

•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

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.

Fine adjustment of the idle 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 anti- clockwise until the chain stops. When the idle speed is correctly adjusted the engine should run smoothly in every position and the engine speed should be safely below the speed at which the chain starts to rotate.

English – 29