Jonsered CS 2147 Maintenance, Carburettor, Function, Basic settings, Fine adjustment, Conditions

MAINTENANCE

Carburettor

Your Jonsered product has been designed and manufactured to specifications that reduce harmful exhaust fumes. The engine will be run in after it has used 8-10 tanks of fuel. To ensure that the engine runs at peak performance and produces as little harmful exhaust fumes as possible after the running-in period, ask your dealer/service workshop (which has a rev counter for this purpose) to adjust your carburettor.

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

LH

T

•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.

WARNING! The catalytic converter muffler

!gets very hot during and after use. This also applies during idling. Be aware of the fire hazard, especially when working near flammable substances and/or vapours.

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 max. 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 max. fast idle speed must not be exceeded.

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.

	Max. fast idle speed, rpm	Idle speed, rpm
CS 2147	14200	2700
CS 2152	13000	2700

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, max. 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.

•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

+ 1/4

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.

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

30 – English