STIHL MS 660 MAGNUM manual Adjusting the Carburetor, Standard Setting, Engine stops while idling

Adjusting the Carburetor

English

Carburetors with H = 1 and L = 1 Adjusting Idle Speed

General Information

The carburetor comes from the factory with a standard setting.

This setting provides an optimum fuel-air mixture under most operating conditions.

Changing the setting of the high speed screw alters the engine's power output and the maximum off-load engine speed.

Standard Setting

NShut off the engine.

NCheck the air filter and clean or replace if necessary.

NCheck the spark arresting screen (not in all models, country-specific) in the muffler and clean or replace if necessary.

H	L
	176BA008 KN

NCarefully screw both adjusting screws down onto their seats (clockwise).

NTurn the high speed screw (H) one full turn counterclockwise.

NTurn the low speed screw (L) one full turn counterclockwise.

Carburetors with H = 3/4 and L = 1/4
H	L
	H	L
		137BA023 KN

NTurn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn).

NTurn the low speed screw (L) carefully clockwise as far as stop, then turn it back 1/4 turn.

NCarry out the standard setting. N Start and warm up the engine.

	L
LA	KN
	137BA024

Engine stops while idling

NTurn the idle speed screw (LA) clockwise until the chain begins to run – then back it off 1/4 turn.

Saw chain runs while engine is idling

NTurn the idle speed screw (LA) counterclockwise until the chain stops moving – then turn it another 1/4 turn in the same direction.

WARNING

If the chain continues moving when the engine is idling, have your saw checked and repaired by your servicing dealer.

Erratic idling behavior, poor acceleration (even though standard setting of low speed screw is correct)

Idle setting is too lean

NTurn the low speed screw (L) counterclockwise, no further than stop on carburetors with L = 1/4, until the engine runs and accelerates smoothly.

MS 660 41