Stihl MS 251 Manual

30 MS 231, MS 231 C, MS 251, MS 251 C
: Inspect the cover (1), spur gear
set (2), tensioner slide (3) and
thrust pad (4) and replace as
necessary.
– Clean all disassembled parts,
b 14
– Lubricate thread and gears with
STIHL multipurpose grease,
b 14
– Reassemble in the reverse
sequence.
5.5.1 Quick Chain
Tensioner
The quick chain tensioner is
installed in the sprocket cover.
: Apply tool to the side (arrow) of
the wing nut (1) and carefully pry
it out of the sprocket cover.
– Check the wing nut (1) and
replace if necessary
42
1 3
2
533RA058 TG
1
165RA469 TG
– Swing the wing nut (1) upright.
: Push the wing nut (1), thin side
first (see arrow), into the opening
and press it down until it snaps
into position.
: Take out the screw (arrow).
: Remove the cover plate (1) and
adjusting wheel (2).
When installing the adjusting wheel,
make sure its teeth face the cover
plate.
– Reassemble in the reverse
sequence.
1
165RA007 TG
2310RA045 TG
1
2
5.5.2 Chain Catcher
– Remove the chain sprocket
cover.
The chain catcher (arrow) is an
integral part of the sprocket
cover (1).
– If the chain catcher is damaged
or worn, install a replacement
chain catcher.
: Position the replacement chain
catcher (1) so that it lines up with
the contour of the
recess (arrows).
: Insert and tighten down the
screw (2) firmly.
– Reassemble in the reverse
sequence.
2310RA048 TG
1
2310RA428 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