Husqvarna 343FRM User Manual

English

 –

 29

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.

The carburettor can be designed in different ways, 
depending on the existing environmental and emissions 
legislation. Some machines are equipped with movement 
limiters on the carburettor’s adjuster screws. These limit 
the adjustment range to a maximum of 1/2 turn.

•

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.

•

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 cutting attachment rotates when the 
engine is idling the idle adjustment screw T should be 
turned anti-clockwise until the cutting attachment stops.

Rec. idle speed: See the Technical data section.

Recommended max. speed: See the Technical data 
section.

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.

•

Before any adjustments are made, make sure that the 
air filter is clean and the air filter cover is fitted. If you 
adjust the carburettor when the air filter is dirty it will 
result in a leaner mixture when the filter is finally 
cleaned. This can lead 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 cutting attachment rotates when the 
engine is idling the idle adjustment screw T should be 
turned anti-clockwise until the cutting attachment 
stops.