CARBURETTOR
English – 37
H
L
+ 1/4
Low speed jet L
The idling speed is set with the screw marked T.
If adjustment is necessary, screw in (clockwise) the idling
screw T with the engine running until the chain begins to go
round. Now screw out (anticlockwise) until the chain stops
turning. A correctly set idling speed is when the engine runs
smoothly in all positions with a good margin to the speed
when the chain starts to turn.
WARNING!
Do not use the chainsaw until it has been
adjusted to prevent the chain going
round at idling speed.
!
A correctly adjusted carburettor means that the chainsaw
accelerates without hesitation and that it splutters somewhat
at full throttle. In addition, the chain should not go round at
idling speed. If the L-screw is set too lean this can cause
starting problems and poor acceleration. If the H-screw is set
too lean this will give the chainsaw less power, poor
acceleration, and/or will damage the engine. If both the L and
H screws have an over-rich setting this will give acceleration
problems or reduce the working speed.
The high speed jet H affects the chainsaw’s power and speed.
A too lean high speed jet setting (H-jet screwed in too far) gives
over revving on the saw, resulting in damage to the engine. Run
the chainsaw at full throttle for about 10 seconds. Then turn the
H-screw anticlockwise 1/4 of a turn. Run the chainsaw again
at full throttle for approx. 10 second seconds and listen to the
difference in the overspeed. Repeat this procedure with the H-
screw turned an additional 1/4 of a turn anticlockwise.
You have now run the chainsaw at H ±0, H = +1/4, and H =
+1/2 from the basic settings. At full throttle the engine will have
sounded different for each setting. The H-screw is set correctly
when the chainsaw “splutters” somewhat. If the saw “screams”
then the setting is too lean. If the muffler emits a lot of smoke,
at the same time as the chainsaw splutters a lot, then the
setting is too rich. Turn the H-screw clockwise until you find
the setting that sounds right.
Fine tuning of idling T
Find the highest idling speed by slowly turning the low speed
screw clockwise then anticlockwise. When the highest speed
has been found, turn the L-screw anticlockwise 1/8 - 1/4 of a
turn.
High speed jet H
Correctly adjusted carburettor
NOTE! If the chain goes round at idling speed the
T-screw should be turned anticlockwise until it stops.
NOTE! A tachometer should be used to
achieve an optimal setting. The recommended
max. overspeed must not be exceeded.
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