Stihl MS 251 Manual

79MS 231, MS 231 C, MS 251, MS 251 C
: Pull the worm (1) with drive
spring (2) out of the oil pump.
– Check the spring and worm and
replace if necessary.
: Take out the screw (1), lift the oil
pump (2) and push the hose (3)
out of its seat (arrow).
: Pull the oil pump (1) off the oil
suction hose (2).
2310RA302 TG
1
2
2310RA303 TG
1
3
2
2
2310RA304 TG
1
: Pull the hose (1) off the nipple.
– Check the oil pump and replace it
if necessary
Installing
: Position the hose (1) so that the
ribs (arrows) are in alignment.
: Position the oil suction hose (1)
so that the straight sides of the
lugs (arrows) locate against the
engine housing.
: Push the oil suction hose (1) onto
the nipple.
2310RA305 TG
1
2310RA306 TG
1
2310RA307 TG
1
: Place oil pump (1) in position and
push the tube (2) into its
seat (arrow) until it is flush with
the engine housing.
: Fit the screw (3)
and tighten it down firmly.
– Push the worm home as far as
stop – it must rotate freely.
: Push the washer (1) into position.
Installed position is correct when
"TOP" (arrow) faces outwards.
– Reassemble all other parts in the
reverse sequence.
2310RA308 TG
3
2
1
TOP
2310RA309 TG
1
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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