Stihl MS 251 Manual

99MS 231, MS 231 C, MS 251, MS 251 C
Installing
: Position the intake manifold (1)
on the cylinder.
: Insert the screws (arrows) and
tighten them down firmly.
– Install the air guide shroud,
b 12.4
Models with manual fuel pump,
b 12.4.1
– Install the carburetor carrier,
b 12.8
– Reassemble all other parts in the
reverse sequence.
12.10 Tank Vent
12.10.1 Testing
If problems occur on the carburetor
or the fuel supply system, also
check and clean the tank vent and
replace it if necessary. Check
function by performing pressure and
vacuum tests on the tank via the fuel
hose.
– Open the fuel tank cap and drain
the fuel tank, b 1.
– Close the tank cap.
– Remove the carburetor, b 12.5
2310RA360 TG
1
: Push the
nipple (1) 0000 855 9200 into the
fuel hose (arrow).
Models with manual fuel pump
: Use a suitable plug (2) to seal the
fuel suction hose (1).
2310RA361 TG
1
2
2310RA362 TG
1
Vacuum test
: Push the ring (1) to the left and
connect the pump (2)
0000 850 1300 to the
nipple (arrow)
– create a vacuum in the fuel
tank.
Equalization of pressure takes
place via the tank vent. There must
be no buildup of vacuum in the fuel
tank.
– Clean the area around the tank
vent.
– If necessary, install a new tank
vent or fuel tank, b 12.10 or
b 12.11.5
2310RA363 TG
1
2
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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