Husqvarna 125C Workshop Manual page 26

502 71 14-01
High speed needle H
The high speed needle H affects the engine power, speed,
temperature and fuel consumption. If the high speed needle
is set too lean (screwed in too far) the engine speed will be
too high and cause engine damage. Do not let the engine
run at full speed for more than 10 seconds.
Apply full throttle and turn the high speed needle H very
slowly clockwise until the engine slows down.
Now turn the needle very slowly anticlockwise until the
engine starts to run unevenly. Now turn the needle slowly
clockwise until the engine runs smoothly.
Fuel system
Basic setting
The carburettor is set to its basic setting when test run at the factory. The basic
setting is "richer" than the optimal setting (fast idle speed is 600–800 rpm under the
recommended max. speed) and should be kept during the engine's first working
hours. Thereafter the carburettor should be fine tuned.
The default setting is:
H = 1 1/2 revolution open
L = 1 1/2 revolution open
Fine adjustment
Fine adjustment of the carburettor should be carried out after the engine has been
"run-in".
• The air filter should be clean and the cylinder cover fitted when all adjustments
are made.
First adjust the L-needle, then the H-needle and finally the idling speed's T-
screw.
Idling speed = 2,800 – 3 200 r/min.
• At full throttle, the H-needle shall have a setting so that the engine is almost
splutters.
530 03 55-60
NOTE!
A tachometer should always be used to find 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.
NOTE!
If the cutting equipment rotates while idling the T-
screw should be turned anticlockwise until it stops.
Correctly adjusted carburettor
A correctly adjusted carburettor means that the engine
accelerates without hesitation and it four-strokes a little at full
throttle.
• The cutting equipment must not rotate while idling.
• A too lean adjusted L-needle can cause starting difficulties
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 accelera-
tion problems or a too low working speed.
3
25