18
English
BR 420
Standard Setting
:
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.
Adjusting Idle Speed
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
screw (
L
).
Fine tuning for operation at high
altitude
A slight correction of the setting may be
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.
H
L
373BA043 KN
LA
L
373BA044 KN