Husqvarna 1153158-95, Operator'S Manual

MAINTENANCE

30 – English

Carburetor

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

Function

•

The carburetor governs the engine’s speed via the 
throttle control. Air and fuel are mixed in the 
carburetor. The air/fuel mixture is adjustable. Correct 
adjustment is essential to get the best performance 
from the machine.

•

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

•

The carburetor 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 carburetor 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.

CAUTION! 

If the chain rotates while idling the T-screw 

must be turned anti-clockwise until the chain stops.

Rec. idle speed:

2800 rpm

Fine adjustment

When the machine has been ”run-in” the carburetor 
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.

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 
carburetor 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.

•

Carefully turn both jets, L and H, so that they are 
midway between fully screwed in and fully screwed 
out.

•

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. 
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

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! 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.

H

L

T

!

WARNING! Contact your servicing 
dealer, if the idle speed setting cannot be 
adjusted so that the chain stops at idle. 
Do not use the chain saw until it has 
been properly adjusted or repaired.