Stihl 038 - Carburetor; Basic setting

Carburetor
1 =High speed adjusting screw
2 = Low speed adjusting screw
3 = Idle speed adjusting screw
The carburetor has been adjusted for optimum perform-
ance under the barometric pressure and climatic condi-
tions at the factory (800 m/1000 ft above sea level). If the
conditions at your operating site are different, it may be
necessary to change the carburetor setting to achieve
maximum engine power.
Make the correction with adjusting screws 1 and 2 (1 for
full load and 2 for idle). Turn screws clockwise (leaner) for
high altitude operation or counterclockwise (richer) for
operation at sea level.
Note that even slight alterations on the adjusting screws
have a noticeable effect on the engine’s running behavior.
Only carry out carburetor adjustments after cleaning the
air filter and warming up the engine.
Caution: The setting of the high speed adjusting screw
not only affects power output but also the maximum off-
load engine speed. If the setting is too lean (screw turned
too far clockwise), the maximum permissible engine
speed will be exceeded. This can cause engine damage,
Regulating idle speed adjusting screw
brought
about
by
lack
of
lubrication
and
overheating
in
particular.
Corrections
to
the
setting
of
the
high
speed
adjusting
screw
may
be
carried
out
only
if
an
accurate
ta-
chometer
is
available
to
check
the
maximum
engine
speed
of
12,500
r.p.m.
(with
bar
and
correctly
tensioned
chain).
Basic setting
If it is necessary to readjust the carburetor again from the
beginning,
first
carry
out
the
basic
setting
to
obtain
a
start-
ing point for fine adjustment. To do this, carefully screw the
two
adjusting
screws
down
onto
their
seats
(clockwise).
Then make the following adjustment:
High speed adjusting screw H: back off 1 complete turn
Low speed adjusting screw L: back off 1 complete turn
If
you
have
no
means
of
checking
the
maximum
engine
speed,
do
not
set
the
high
speed
adjusting
screw
any
leaner
by
turning
it
beyond
the
basic
setting.
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