BR 500, BR 550, BR 600
English
20
Standard Setting
N
Shut off the engine.
N
Check the air filter and clean or
replace if necessary.
N
Check that the throttle cable is
properly adjusted – readjust if
necessary – see chapter on
"Adjusting the Throttle Cable".
N
Check the spark arresting screen
(not in all models, country-specific)
in the muffler and clean or replace if
necessary.
N
Carefully turn both adjusting screws
counterclockwise as far as stop:
N
The high speed screw (H) is 3/4 turn
open.
N
The low speed screw (L) is 3/4 turn
open.
Adjusting Idle Speed
N
Carry out standard setting.
N
Start and warm up the engine.
Engine stops while idling
N
Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly.
Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
N
Turn the low speed screw (L)
counterclockwise, no further than
stop, until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
N
Turn the low speed screw (L)
clockwise, no further than stop, until
the 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).
Fine Tuning for Operation at High
Altitude
A slight correction of the setting may be
necessary if the engine does not run
satisfactorily:
N
Carry out standard setting.
N
Warm up the engine.
N
Turn high speed screw (H) slightly
clockwise (leaner) – no further than
stop.
NOTICE
After returning from high altitude, reset
the carburetor to the standard setting.
If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.
N
If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N
Fit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the Spark Plug
N
Pull off the spark plug boot (1).
N
Unscrew the spark plug (2).
H
L
Spark Plug
2
452BA092 KN
