Stihl MS 251 Manual

93MS 231, MS 231 C, MS 251, MS 251 C
Installing
: Position the lever (1) so that its
hook engages the lever on the
choke shaft (arrows).
: Push the lever (1) onto the
throttle shaft (2) so that it
engages the flats on the end of
the shaft.
: Fit the retaining ring (3).
: Check operation
– lever (1) must engage
lever (4) (arrows).
– Reassemble all other parts in the
reverse sequence.
2310RA272 TG
3
4
1
2
12.6.5 Adjusting Screws
– Remove the carburetor, b 12.5
– See also carburetor
troubleshooting, b 3.6
There are three adjusting screws on
the carburetor:
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 has a
limiter cap, which has to be
removed before the screw is
removed.
Always install a new limiter cap.
Low speed screw
: Take out the low speed screw
L (1).
2310RA273 TG
1
3
2
2310RA274 TG
1
: Inspect the tip (arrow) and
O-ring (1) for damage or wear
and replace the low speed screw
(L) if necessary.
– Screw down the low speed screw
(L) as far as stop.
– Continue with the high speed
screw H.
High speed screw
The high speed screw H has a
limiter cap, which has to be
removed before the screw is
removed.
: Rotate the limiter cap until the
lug (1) is in line with the
slot (arrow).
2310RA275 TG
1
1
2310RA276 TG
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Stihl MS 251 Specifications

General

Idle speed	2800 RPM
Motor type	2-stroke motor
Chain pitch	1/308 \
Blade length	450 mm
Product color	Black, Grey, Orange
Motor speed (max)	10000 RPM
Oil tank capacity	0.2 L
Fuel tank capacity	0.39 L
Engine displacement	45.6 cm³
Kickback protection	Yes
Engine power	3 hp
Power source	Gasoline
Sound power level	114 dB
Vibration emission	3.9 m/s²
Sound pressure level	103 dB

Weight and Dimensions

Weight	4900 g