Maintenance, Carburettor adjustment | Jonsered CS 2171WH guide

MAINTENANCE

Carburettor adjustment

The carburettor can be designed in different ways, depending on existing environmental and emissions legislation. Some chain saws are equipped with movement limiters on the carburettor’s adjuster screws. These limit the adjustment possibilities to a maximum of a 1/2 turn.

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When your chain saw is equipped with a carburettor that features movement limiters, the carburettor should be adjusted according to the instructions under the heading Carburettor with movement limiters.

When your chain saw is equipped with a carburettor that does not feature movement limiters, the carburettor should be adjusted according to the instructions under the heading Carburettor without movement limiters.

Contact your servicing dealer (retailer) if you are uncertain of which type of carburettor your chain saw is equipped with.

Carburettor with movement limiters

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Your Jonsered product has been designed and manufactured to speciﬁcations that reduce harmful exhaust fumes.

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.

•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

•The L and H-jets are used to adjust the supply of fuel to match the rate that air is admitted, which is controlled with the throttle. If they are screwed clockwise the air/fuel ratio becomes leaner (less fuel) and if they are turned anti- clockwise the ratio becomes richer (more fuel). A lean mixture gives a higher engine speed and a rich mixture gives a lower engine speed.

•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. Avoid running at a too high speed during the ﬁrst 10 hours.

CAUTION! If the chain rotates while idling the T-screw must be turned anti-clockwise until the chain stops.

Rec. idle speed: 2700 rpm

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.

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.

Changing the type of fuel

Fine tuning may be required if the chain saw, after changing the type of fuel, performs differently with regard to starting, acceleration, maximum speed, etc.

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.

•Do not attempt to adjust the L and H jets beyond either stop as this could cause damage.

•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.

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