STIHL 064, 066 85
11.6 Carburetor Adjustment
(Analog Ignition)
Adjusting screws on carburetor
1 = High speed adjusting screw
2 = Low speed adjusting screw
3 = Idle s
eed ad
ustin
screw
- Turn clockwise for a leaner mix- Basic setting
ture (at high altitudes).
If the carburetor has to be ad-
- Turn counterclockwise for a justed from scratch, carefully
richer mixture (at sea level). screw both adjusting screws clock-
wise down onto their seats to ob-
Important: Note that even very tain a starting point for fine tuning.
slight variations at the adjusting
screws produce a noticeable Then make the following adjust-
change in engine running behavior. ments:
Note: Always make sure that the High speed adjusting screw H:
engine is warm and the air filter back off 1 full turn
clean before carrying out carbure-
tor adjustments. Low speed adjusting screw L:
back off 1 full turn
When the engine is tested at the Caution: The setting of the high
factory the carburetor is set to speed adjusting screw not only af- The saw must be run with the
obtain a slightly richer mixture fects the engine's performance but basic carburetor setting (H = 1,
to provide the cylinder bore and also its maximum off-load speed. L = 1) if an accurate tachometer
bearings with additional lubricant If the setting is too lean (adjusting is not available for checking the
during the break-in period. This screw turned too far clockwise), engine's maximum speed.
setting should be left as it is for the maximum permissible engine
the first three tank fillings. The speed will be exceeded. This can Notes for adjustment of idle
high speed adjusting screw may result in damage to the engine speed
then be turned up to 1/4 turn clock- being caused by a lack of lubricant
wise to obtain a leaner mixture. and overheating. Engine stops while idling:
Caution: The engine's maximum Corrections to the high speed ad- - Turn idle speed adjusting screw
permissible speed with bar and justing screw may only be carried clockwise until the chain begins
chain must not be exceeded. out if the maximum permissible en- to run.
gine speed of 12,000 rpm (with bar
If the saw is used at high altitudes and properly tensioned chain) can - Then turn it back one quarter turn.
(mountains) or near sea level, it be checked with an accurate ta-
may be necessary to alter the car- chometer. Chain runs while engine is
buretor setting slightly. This correc- idling
tion is made at the two adjusting
screws (H and L) as follows: - Turn the idle speed adjusting
screw counterclockwise until the
chain stops running.
- Then turn it about another quar-
ter turn in the same direction.
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