Adjusting The Carburetor; Basic Setting - Stihl MS 261 User Manual

12.7

Adjusting the Carburetor

12.7.1 Basic Setting

The basic setting is necessary only
if the high speed screw (H) or low
speed screw (L) has to be replaced
or after cleaning and adjusting the
carburetor from scratch.
It is necessary to carry out the basic
setting after removing the limiter
cap.
The carburetor, air filter and
grommet are installed, the adjusting
screws fitted and the new limiter cap
pre-installed.
– Check chain tension and adjust if
necessary.
– Inspect the spark arresting
screen (if fitted) and clean or
replace if necessary, b 3.7 or
b 6.1
– Check the air filter and clean or
replace if necessary, b 12.1
2
For the sake of clarity the adjusting
screws are shown on the exposed
carburetor.
: Starting with the high speed
screw H (1) against its seat,
open it 1 1/2 turns
counterclockwise
– this is the basic setting.
118
: Starting the with low speed
screw L (2) against its seat, open
it 1 full turn counterclockwise
– this is the basic setting.
– Warm up the engine.
Setting disk 5910 893 6600 may be
fitted on the screwdriver
5910 890 2306 to simplify
adjustments.
: Insert screwdriver (1)
5910 890 2306 through the
opening (arrow) and into the low
speed screw L and high speed
screw H
– push the screwdriver through
the pre-installed limiter cap on
the high speed screw H.
Adjust idle speed with a tachometer.
Adjust specified engine speeds
within a tolerance of ± 200 rpm.
1
1. Adjust engine speed with
idle speed screw (LA),
to 3,300 rpm.
2. Turn the
low speed screw (L)
counterclockwise or clockwise
to obtain
maximum engine speed.
If this speed is higher than
3,700 rpm, abort the procedure and
start again with step 1.
3. Use the
idle speed screw (LA
) to set the engine speed again to
3,300 rpm.
4. Use the low speed screw (L
) to set engine speed to
2,800 rpm.
5. Use the high speed screw( H
) to set the maximum engine
speed to
14,000 rpm.
1
Checking position of limiter cap
Notch (arrow) in limiter cap (1) must
point vertically upwards.
: If necessary, use a suitable
screwdriver to rotate the limiter
cap (1) clockwise as far as stop
– the notch (arrow) is at the top.
1
MS 261, MS 261 C