Stihl SR 340 Instruction Manual page 29

English / USA
Standard Setting
H
: Shut off the engine.
: Check the air filter and clean or
replace if necessary.
: Check the spark arresting screen (if
fitted) in the muffler and clean or
replace if necessary.
: Carefuly turn both adjusting screws
counterclockwise as far as stop:
High speed screw (H) is now open
1/4 turn
Low speed screw (L) is now open
1/4 turn
: Start and warm up the engine.
28
Adjusting Idle Speed
L
Engine stops while idling
: Turn the idle speed screw (LA)
clockwise until the engine runs
smoothly.
Erratic idling behavior, engine stalls
even after re-adjusting LA screw,
poor acceleration
Idle setting is too lean:
: Turn low speed screw (L)
counterclockwise – no further than
stop – until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting is too rich:
: Turn low speed screw (L) clockwise
– no further than stop – until the
engine runs and still accelerates
smoothly.
It is usually necessary to change the
setting of the idle speed screw (LA)
after every correction to the low speed
L
screw (L).
Fine tuning for operation at high
altitude
A slight correction of the setting may be
LA
necessary if engine power is not
satisfactory:
: Check standard setting.
: Warm up the engine.
: Turn the high speed screw (H)
clockwise (leaner) – no further than
stop.
If the setting is too lean, there is a
risk of engine damage due to
insufficient lubrication and
overheating.
SR 340, SR 420