Fine adjustment of the idle speed T
Adjust the idle speed using the idle adjustment screw T, if it is
necessary to readjust. First turn the idle adjustment screw T
clockwise until the cutting attachment starts to rotate. Then
turn the screw anticlockwise until the cutting attachment
stops. The idle speed is correctly adjusted when the engine
will run smoothly in every position. The idle speed should also
be well below the speed at which the cutting attachment starts
WARNING! If the idle speed cannot be
adjusted so that the cutting attachment
stops, contact your dealer/service
workshop. Do not use the machine until it
has been correctly adjusted or repaired.
High speed jet H
The high speed jet H affects the engine power, speed,
temperature and fuel consumption. If the high speed jet H 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 jet H very slowly
clockwise until the engine slows down. Then turn the high
speed jet H very slowly anticlockwise until the engine starts to
run unevenly. Now turn the high speed jet H slowly clockwise
a little way until the engine runs smoothly.
Note that the engine should not be under load when you
adjust the high speed jet H. You should therefore remove the
cutting attachment, nut, support ﬂange and drive disc before
adjusting the high speed jet H.
The high speed jet H is adjusted correctly when the machine
burbles a little. If the machine races then the setting is too
lean. If the engine produces a lot of smoke and burbles a lot
then the setting is too rich.
CAUTION! For optimum adjustment of the carburettor,
contact a qualiﬁed dealer/service workshop that has a
revolution counter at their disposal.
Correctly adjusted carburetor
When the carburetor is correctly adjusted the machine will
accelerate without hesitation and burble a little at maximum
speed. It is also important that the cutting attachment does
not rotate at idle. If the low speed jet L is set too lean it may
cause starting difﬁculties and poor acceleration.
If the high speed jet H is set too lean it will result in less power,
less performance, poor acceleration and/or damage to the
If both the L and H jets are set too rich it will results in
acceleration problems or too low a working speed.
CAUTION! Some mufﬂers are ﬁtted with a catalytic
converter. See chapter on Technical data to see whether your
machine is ﬁtted with a catalytic converter.
The mufﬂer is designed to reduce the noise level and to direct
the exhaust gases away from the operator. The exhaust
gases are hot and can contain sparks, which may cause ﬁre
if directed against dry and combustible material.
Some mufﬂers are equipped with a special spark arrestor
screen. If your machine has this type of mufﬂer, you should
clean the screen at least once a week. This is best done with
a wire brush.
On mufﬂers without a catalytic converter the screen should be
cleaned weekly, or replaced if necessary. On mufﬂers ﬁtted
with a catalytic converter the screen should be checked, and
if necessary cleaned, monthly. If the screen is damaged it
should be replaced.
If the screen is frequently blocked, this can be a sign that the
performance of the catalytic converter is impaired. Contact
your dealer to inspect the mufﬂer. A blocked screen will cause
the machine to overheat and result in damage to the cylinder
and piston. See also instructions under the heading
CAUTION! Never use a machine with a defective mufﬂer.
WARNING! Mufﬂers ﬁtted with catalytic
converters get very hot during use and
remain so for some time after stopping. This
also applies at idle speed. Contact can result
in burns to the skin. Remember the risk of
1151475-95 Rev. 1 2009-01-16