Makita DCS 7901 Adjusting the carburetor, Working in winter, Important information, Basic setting

Adjusting the carburetor

Important information:

The carburetorof this tool is fitted with limiter caps which restrict the range of adjustmentand prevents over-richmixture settings. This ensures providing good engine power and efficient fuel consumption. Beforeinstallingthe limiter caps, the manufacturer performs the "Basic Setting" procedure.

Carburetor adjustment is necessary for optimum engine performance, for safer and more economical operation. The engine should be warm, the air filter clean, and the chain properly tensioned. Have carburetor adjustment done by an authorised MAKITA service centre.

The carburetor is factory-adjusted for the air pressure at sea level. At other elevations or under other conditions of weather, temperature,or humidity, or when breaking in a new engine, it may be necessaryto makeslight adjustmentsto the carburetor.

You will need a tachometer (9, part No. 950 233 210) for optimum adjustment.

Do not go below the specified basic setting of the main nozzle (H). Doing so may cause engine damage due to overheating and insufficient lubrication!

Use the supplied carburetor screwdriver (8) for carburetor adjustment.Ithasa moulded-onprojectionthat aids inadjusting.

Before undertaking the adjustcent, run the engine for 3-5 minutes to warm it up, but not at high speed!

For proper adjustment, proceed as follows:

1.Basic setting (engine off) Start engine and warm up.

2.Set idle

3.Check top speed

4.Check acceleration

5.Check idle speed

Repeat steps 2-5until you get the right idle speed, good acceleration and maximum permissible

1.Basic setting

Carefully turn the adjusting screw for the idle nozzle (L) clockwise until you feel a stop.

Turn adjusting screw (L) 1 turns counter-clockwise.

LH

2.Set idle

Set the idle speed per the technical specifications.

Turningthe adjusting screw (S) in (clockwise)increases the idle speed. Turning it out (counter-clockwise)lowers the idle speed. In no case should the chain move.

3.Check top speed

The top speed in the governor can be clearly heardfrom the ignition misses. Important: To prevent engine

damage, never go more than a 114 turn in clockwise with adjusting screw (H).Note: Since there is an electronic speed governor (limiter) at 13,500 rpm that cuts off the ignition current, the top speed cannot be read from the tachometer.

4.Check acceleration

When the throttle is pressed, the engine should go

smoothly from idle to high speed. If this is too slow, turn the adjusting screw (L)in small (max. 118 turns) incre- ments counter-clockwise.

5.Check idle speed

Check the idle speed after setting the top speed (the chain must not move).

Repeatthe adjustment procedurestartingat Step 2, until

the engine runs with the correct idle speed, good

acceleration, and top speed.k

I

Working in winter

In order to prevent carburetor icing in conditions of low temperature combined with high humidity, and below + 5°C in order to get up to operating temperature faster, heated air can be taken from the cylinder.

Remove the filter hood (see ,,Cleaning air filtef)

Remove the insert (10)and insert it as shown in position B for				1
cold-weather operation.
At temperatures above + 5°C the carburetor must NOT be fed
heated air. Failure to follow these instructions can lead to
damage to the cylinder and piston!
At temperatures over +5"C place the insert in position A for
normal operation.
Position A	-	Normal operation	,
Position B $&	-	Cold-weather operation

Reinstall the filter hood.

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