Carburetor Adjustment - Stihl 020 T Service Manual

10.3

Carburetor Adjustment

Standard setting
If the carburetor has to be adjusted
from scratch, first carry out the
standard setting.
• Carefully screw in both adjusting
screws clockwise until they are
hard against their seats.
Now make the following adjust-
ments:
H =
High speed adjusting screw (1)
backed off 1 full turn
L =
Low speed adjusting screw (2)
backed off 1 full turn
Note: If no tachometer is avail-
able, do not turn the high speed
adjusting screw beyond the
standard setting to make the
mixture leaner.
A minor correction may be neces-
sary if the saw is used at high alti-
tudes (mountains) or near sea le-
vel.
For corrections to high speed
adjusting screw (H):
Use a tachometer - do not
exceed max. permissible engine
speed.
Engine can be damaged by lack of
lubricant and overheating.
Maximum engine speed with bar
and properly tensioned chain:
14,500 r.p.m.
STIHL 020 T
• Check chain tension.
• Check air filter and clean if
necessary.
• Adjust idle speed correctly
(chain must not rotate)
• Start the saw –
warm up the engine.
Turn high speed adjusting screw (H)
and low speed adjusting screw (L)
clockwise for leaner mixture at high
altitudes or counterclockwise for richer
mixture at sea level.
Turn screws very slowly and care-
fully - even slight adjustments
produce a noticeable change in
engine running behavior.
Corrections to high speed adjusting
screw:
The setting of the high speed
adjusting screw (H) affects the
maximum off-load engine speed.
If the setting is too lean, the
maximum permissible engine
speed will be exceeded and
increase the risk of engine
damage.
Adjusting engine idle speed:
A correction at the low speed
adjusting screw (L) usually
necessitates a change in the
setting of the idle speed stop
screw (LA) (3).
Engine stops while idling
Check standard setting. Turn idle
speed stop screw (LA) clockwise
until the chain begins to run - then
turn it back one quarter turn.
Chain runs while engine is
idling:
Check standard setting.
Turn the idle speed stop screw
(LA) counterclockwise until the
chain stops running - and then
turn it about another quarter turn
in the same direction.
Erratic idling behavior, poor
acceleration:
Idle setting too lean. Turn the low
speed adjusting screw (L) counter-
clockwise until the engine runs and
accelerates smoothly.
Exhaust smokes at idle speed:
Idle setting too rich.
Turn the low speed adjusting screw
(L) clockwise until the engine speed
drops - and then turn it back one
quarter turn - and check that the
engine accelerates smoothly when
the throttle is opened.
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