Stihl BT 45 Manual page 30

H
LA
Now make the following
adjustments:
: Turn the high speed screw (H)
counterclockwise as far as stop
(no more than 3/4 turn)
: Carefully turn the low speed
screw (L) clockwise until it is
against its seat, then open it one
full turn counterclockwise.
– Start the engine and allow it to
warm up.
: Use the idle speed screw (LA) to
adjust idle so that the drilling
spindle does not rotate.
Fine tuning
A minor correction may be
necessary if engine power is not
satisfactory when operating at high
altitude or at sea level. Note that
even very slight corrections to the
high speed screw (H) produce a
noticeable change in engine
running behavior.
– Carry out the standard setting.
– Start the engine and allow it to
warm up.
– Open the throttle wide.
BT 45
– At high altitude (mountains): Turn
L
the high speed screw (H)
clockwise (leaner), but no further
than stop, until there is no
noticeable increase in engine
speed.
– At sea level: Turn the high speed
screw (H) counterclockwise
(richer), but no further than stop,
until there is no noticeable
increase in engine speed.
It is possible that the standard
setting produces the highest engine
rpm in both the above cases.
Adjusting idle speed
– Open the idle speed screw (L)
one full turn.
– Allow the engine to warm up.
Engine stops while idling
– Turn the idle speed screw (LA )
slowly clockwise until the engine
runs smoothly. The drilling
spindle must not rotate.
Drilling spindle rotates while
engine is idling:
– Turn the idle speed screw (LA)
counterclockwise until the drilling
spindle stops rotating. Then turn
the screw about another half to
one full turn in the same direction.
Erratic idling behavior, poor
acceleration
– Idle setting is too lean. Turn the
low speed screw (L) counter-
clockwise (about a quarter turn)
until the engine runs and
accelerates smoothly.
Erratic idling behavior
– Idle setting is too rich. Turn the
low speed screw (L) clockwise
(about a quarter turn) 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).
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