Jonsered BC 2255 Service Manual

English

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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.

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.

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.

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. 

CAUTION!  For optimum adjustment of the carburettor, 
contact a qualified dealer/service workshop that has a 
revolution counter at their disposal. 

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 engine. 
If both the L and H jets are set too rich it will results in 
acceleration problems or too low a working speed.

The correct start throttle speed is set by means of an adjuster 
on the rear of the handle next to the cable. Use this screw (5 
mm Allen screw) to increase or decrease the start throttle 
speed.

1

Run the machine at idle.

2

Press the start throttle lock as described under the 
heading Starting and stopping.

3

If the start throttle speed is too low (below 4000 rpm), turn 
the adjuster screw A clockwise until the cutting 
attachment starts to rotate. Then turn A clockwise a 
further 1/2 turn.

4

If the start throttle speed is too high, turn the adjuster 
screw A anticlockwise until the cutting attachment stops. 
Then turn adjuster screw A clockwise a further 1/2 turn.

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.

H