Checking The Spark Plug - Stihl MS 381 Instruction Manual

English
Adjusting Idle Speed
L
Engine stops while idling
: Open the low speed screw (L) one
full turn.
: Turn the idle speed screw (LA)
clockwise until chain begins to run –
then turn it back one quarter of a
turn.
Chain runs when engine is idling
: Open the low speed screw (L) one
full turn.
: Turn the idle speed screw (LA)
counterclockwise until chain stops
running – then turn screw another
quarter turn in the same direction.
32
Erratic idling behavior, poor
acceleration
(even though the low speed screw is
opened one turn)
Idle setting is too lean.
: Turn the low speed screw (L)
counterclockwise until engine
runs and accelerates smoothly.
It is usually necessary to change the
setting of the idle speed screw (LA)
after every correction to the low speed
screw (L).

Checking the Spark Plug

If engine is down on power, difficult to
start or runs poorly at idle speed, first
check the spark plug.
: Remove the spark plug –
see "Starting / Stopping the Engine".
: Clean dirty spark plug.
: Check electrode gap (A) and
readjust if necessary – see
"Specifications".
MS 381