Jonsered GR50 - Manual (Page 26)

26 – English
MAINTENANCE
Low speed jet L
Try to find the highest idling speed, turning the low speed
needle L clockwise respectively counter-clockwise. When the
highest speed has been found, turn the low speed needle L 1/
4 turn counter-clockwise.
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
to rotate.
High speed jet H (GR41, GR50, RS44)
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.
High speed jet H (RS52)
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.
Setting procedure without a load (Blade can be
used)
The machine is equipped with speed control in the ignition
system. It is extremely important to be aware of this when
adjusting the carburettor.
RS52: Speed control at: 13500 rpm
When attempting to adjust the speed over that specified, the
speed is not changed, but only causes the engine to receive
too little fuel resulting in a large risk of engine failure.
Run the machine warm for approximately 5 minutes
alternating between short intervals of full throttle and idling.
When the carburettor is to be adjusted, apply full throttle and
turn the H-needle anti-clockwise until the engine speed
reaches 10,500-11,000 r/min (burbles) or until the cap
reaches its stop position. Now turn the H-needle slowly
clockwise until the engine reaches the speed when the speed
control comes into force. In some cases, speed control can
come into force at 200-300 revs below or above that specified.
It is important that you do not continue to turn the H-needle
clockwise when the engine speed has stabilised. Screw the
H-needle (anti-clockwise) a few tenths of a turn instead.
Setting procedure with a load (Trimmer head
should be used)
Ensure the length of the trimmer cord is correct, i.e. exactly
reaches the knife on the trimmer guard. Use either 3 mm or
3.3 mm diameter trimmer cord.
Run the machine warm for about 5 minutes mostly at full
throttle. When the carburettor is to be adjusted, apply full
throttle and turn the H-needle anti-clockwise until the engine
burbles or until the cap reaches its stop position. (If the engine
runs smoothly when the cap is in its stop position no further
adjustment is necessary!) Turn the H-needle slowly clockwise
until the engine runs absolutely smoothly. (Burbling has
stopped completely). Now screw the H-needle (anti-
clockwise) a few tenths of a turn.
CAUTION! For optimum adjustment of the carburettor,
contact a qualified dealer/service workshop that has a
revolution counter at their disposal.
!
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.
L
+ 1/4
H
H
H