Carburettor Without Movement Limiters - Jonsered CS 2186 Operator's Manual

Fine adjustment of the idle speed T
Adjust the idle speed with the T-screw. If it is necessary to re-
adjust, turn the T-screw clockwise while the engine is running, until
the chain starts to rotate. Then turn anti-clockwise until the chain
stops. When the idle speed is correctly adjusted the engine should
run smoothly in every position and the engine speed should be
safely below the speed at which the chain starts to rotate.
WARNING! Contact your servicing dealer, if
!
the idle speed setting cannot be adjusted so
that the chain stops. Do not use the chain saw
until it has been properly adjusted or repaired.
High speed jet H
At the factory the engine is adjusted at sea level. When
working at a high altitude or in different weather conditions,
temperatures and atmospheric humidity, it may be
necessary to make minor adjustments to the high speed jet.
CAUTION! If the high speed jet is screwed in too far, it
may damage the piston/cylinder.
When test run at the factory, the high speed jet is set so that
the engine satisfies the applicable legal requirements at the
same time as achieving maximum performance. The
carburettor's high speed jet is then locked using a limiter cap
in the fully screwed out position. The limiter cap limits the
potential to adjust the high speed jet to at most half a turn.
CAUTION! There is an integrated speed governor in the
ignition system that limits the maximum speed to 13000 rpm.
The maximum speed will not exceed 13000 rpm when the
high speed jet is adjusted (screwed in). When the speed
governor is activated, you will get the same sound experience
as when the chain saw 4-cycles.
To adjust the carburettor correctly you should contact a
mechanic with access to a rev counter.
CAUTION! As the spark is cut off, the rev counter does not
show speeds higher than 13000 rpm.
Correctly adjusted carburettor
When the carburettor is correctly adjusted the machine
accelerates without hesitation and 4-cycles a little at full throttle.
It is also important that the chain does not rotate at idle. If the L-
jet is set too lean it may cause starting difficulties and poor
acceleration. If the H-jet is set too lean the machine will have less
power, poor acceleration and could suffer damage to the engine.

Carburettor without movement limiters

H
L
Function, Basic settings, Fine adjustment
WARNING! Do not start the chain saw unless
!
the bar, chain and clutch cover (chain brake)
are fitted, otherwise the clutch may come
loose and cause personal injury.
Function
• The carburettor governs the engine's speed via the
throttle control. Air and fuel are mixed in the carburettor.
The air/fuel mixture is adjustable. Correct adjustment is
essential to get the best performance from the machine.
30 –
English
MAINTENANCE
• Adjusting the carburettor means that the engine is
adapted to local operating conditions, e.g. climate,
altitude, petrol and the type of 2-stroke oil.
• The carburettor has three adjustment controls:
- L = Low speed jet
- H = High speed jet
- T = Idle adjustment screw
T
L
• The T-screw regulates the throttle setting at idle speed. If
the T-screw is turned clockwise this gives a higher idle
speed; turning it anti-clockwise gives a lower idle speed.
Basic settings and running in
The basic carburettor settings are adjusted during testing at
the factory. The basic settings are H = 1 turn and L = 1 turn.
To provide the engine's components with good initial
lubrication (during running in) the carburettor should be set for
a richer fuel mixture for the first 3-4 hours that the chain saw
is in use. To do this, adjust the fast idle speed to 600-700 rpm
below the recommended maximum fast idle speed.
If you are unable to check the fast idle speed using a tachometer
the H-jet should not be set for a leaner mixture than given in the
basic settings. The recommended maximum fast idle speed must
not be exceeded. CAUTION! If the chain rotates while idling the
T-screw must be turned anti-clockwise until the chain stops.
Fine adjustment
When the machine has been "run-in" the carburettor should
be finely adjusted. The fine adjustment should be carried out
by a qualified person. First adjust the L-jet, then the idling
screw T and then the H-jet.
Conditions
• Before any adjustments are made the air filter should be
clean and the cylinder cover fitted. Adjusting the
carburettor while a dirty air filter is in use will result in a
leaner mixture next time the filter is cleaned. This can give
rise to serious engine damage.
• Carefully turn the L and H-jets clockwise as far as they will
go. Now turn the jets one turn anti-clockwise. The
carburettor is now set to H = 1 and L = 1.
• Now start the machine according to the starting
instructions and let it warm up for 10 minutes. CAUTION!
If the chain rotates while idling the T-screw must be
turned anti-clockwise until the chain stops.
• Place the machine on a flat surface so that the bar points
away from you and so that the bar and chain do not come
into contact with the surface or other objects.
Low speed jet L
Try to find the highest idle speed by turning the low speed jet
L clockwise then anti-clockwise. When the highest speed has
been found, turn the low speed jet L 1/4 turn anti-clockwise.
L
CAUTION! If the chain rotates while idling the T-screw
must be turned anti-clockwise until the chain stops.
H
+ 1/4