Husqvarna 543RBX Workshop Manual page 37

WARNING: If the cutting attachment does not
stop when you adjust the idle speed, speak to
your servicing dealer. Do not use the product
until it is correctly adjusted or repaired.
• The idle speed is correct when the engine operates
smoothly in all positions. The correct idle speed is
set when the product does not stop and the cutting
equipment does not rotate.
1. Start the engine and operate the product at half
speed for approximately 2 minutes until the engine
becomes warm.
2. Turn the idle adjustment screw clockwise until the
cutting attachment starts to rotate.
Note: The illustration refers to 543RBX, 543RBK, but
the procedure applies also to 553RBX.
3. Turn the idle adjustment screw counterclockwise
until the cutting attachment stops.
Technical data on page 70 for the
Note: Refer to
recommended idle speed.
Carburetor function
The carburetor supplies a mixture of fuel and air to the
engine. The quantity of this mixture is controlled by the
throttle. The proportions of fuel and air in the mixture is
controlled by the adjustable high and low speed jets.
The jets must be correctly adjusted for the engine to
have maximum power at different speeds. A correctly
adjusted carburetor gives the engine maximum power at
different speeds. It also gives the engine a smooth idle
1239 - 001 -
speed and makes it possible to increase engine speed
quickly.
The correct adjustment of the carburetor can change if
the air moisture, temperature and air pressure changes.
The carburetor has 3 adjustment controls.
• L = low speed jet
• H = high speed jet
• T = idle adjustment
553RBX
T
L H
Turn the jets clockwise to get less fuel in the mixture and
counterclockwise to get more fuel in the mixture. Less
fuel in the mixture gives a higher engine speed and
more fuel in the mixture gives lower speed.
The idle adjustment screw adjusts the position of the
throttle when the engine is at idle speed. Turn the idle
adjustment screw clockwise to get a higher idle speed
and turn it counterclockwise to get a lower idle speed.
Carburetor adjustments at the factory
During tests at the factory, the carburetor is adjusted to
give more fuel to the mixture of fuel and air. This
adjustment must be kept during run-in of the engine.
After run-in of the engine, it is necessary to do a fine
adjustment of the carburetor.
543RBX,
543RBK
H 1 ¾ ± ½
L 3 ¼ ± ½
These conditions are necessary to get the correct result:
• The spark plug is not defect and has a correct
electrode gap.
• The air filter is not defect and is clean and correctly
installed.
• There are no leaks between the cylinder and the
distance piece and the carburetor and the insulator.
The screws are tight.
• The fuel filter is clean.
543RBX, 543RBK
T
H L
553RBX
2 ⅞ ± ½
2 ⅛ ± ½
Repair instructions- 37