Throttle - Husqvarna 555FX Workshop Manual

3
Fine adjustment
Fine adjustment of the carburettor should be carried out after the engine has been "run-in".
• The air fi lter should be clean and the cylinder cover fi tted when all adjustments are made.
First adjust the L-needle, then the H-needle and fi nally the idling speed's T-screw.
Idling speed = 2,800 rpm.
• Since the ignition system is limited in terms of rpm, the pre-programmed fast idle speed (12,000 – 13,000 rpm) cannot be
exceeded even if the H-needle is screwed inwards. The risk in this case is still that the engine breaks down as a result of a too
lean fuel/air mix.
• At full throttle, the H-needle shall have a setting so that the engine is almost splutters.
502 71 14-01
530 03 55-60
501 60 02-03
26
Fuel system
Use the 502 71 14-01 tachometer
to check the speed.
• Carefully screw in (clockwise)
the L- and H-jets until they
bottom. Now unscrew (anti-
clockwise) the jets to the
default setting.
Use tool 530 03 55-60.
• Start the engine and run
warm for 5 minutes.
NOTE!
A tachometer should always be used to fi nd the optimal
setting.
The recommended max. speed must not be exceeded.
Idling speed T-screw
Let the engine idle for about 30 seconds or until the speed has
stabilised. Adjust the idling speed T-screw until the engine idles
without stopping.
• Turn the screw clockwise if the engine stops.
• Turn the screw anticlockwise to lower the speed.
Correctly adjusted carburettor
A correctly adjusted carburettor means that the engine
accelerates without hesitation and it "splatters" a little at full

throttle.

• A too lean adjusted L-needle can cause starting diffi culties
and poor acceleration.
• A too lean adjusted H-needle results in lower power, poor
acceleration and/or damage to the engine.
• A too rich setting of the "L" and "H" needles give
acceleration problems or a too low working speed.
NOTE!
If the cutting equipment rotates while idling the T-screw
should be turned anticlockwise until it stops.