Adjusting The Carburetor, Models With M-Tronic; Adjusting The Carburetor, Models Without M-Tronic; 13.7.1 Adjusting Screws - Stihl MS 661 Manual

1 4 5
3
: Position the lever (1) so that the
microswitch's spring (arrow) is
between the lugs (2, 3).
: Rotate leg (4) of torsion spring a
3/4 turn clockwise and attach it to
the lever (1).
: Push the lever (1) onto the choke
shaft so that it engages the flats
on the end of the shaft.
: Fit the E-clip (5).
Leg of torsion spring must be
preloaded and locate against the
carburetor's rib.
Check operation
1
: Move the choke shaft in direction
of cold start }, the lever (1)
must operate the
microswitch (arrow)
– with an audible click.
– Reassemble all other parts in the
reverse sequence.
MS 661, MS 661 C-M
13.6 Adjusting the Carburetor,
Models with M-Tronic
The M-Tronic adjusts the
carburetor. Therefore, no manual
adjustments are necessary or
possible.
2
Shown without switch unit for
greater clarity.
Position of special screw (1) must
not be changed
– changing the factory setting will
cause engine running problems.
: If solenoid valve (2) has been
turned out of position, turn it back
counterclockwise as far as stop
(arrow), then test the solenoid
valve (2), b 8.3.4
– In the event of problems, test the
M-Tronic, b 8.3
13.7

13.7.1 Adjusting Screws

2
3
Illustration with limiter caps.
1
There are three adjusting screws on
the carburetor:
– Adjusting screws (1) and (2) with
limiter caps
H = high speed screw (1)
L = low speed screw (2)
LA = idle speed screw (3)
If the carburetor cannot be adjusted
properly, the problem may be the
adjusting screws.
The high speed screw H and low
speed screw L have limiter caps,
which have to be removed before
the screws are removed.
Always install new limiter caps.
– Remove the carburetor, b 13.4
– See also carburetor
troubleshooting, b 3.6
Adjusting the Carburetor,
Models without M-Tronic
1 2
H L
LA
107