Stihl MS 251 Manual

32 MS 231, MS 231 C, MS 251, MS 251 C
6. Engine
6.1 Muffler
Always check and, if necessary,
repair the fuel system, carburetor,
air filter and ignition system before
looking for faults on the engine.
– Troubleshooting, b 3.7
– Remove the shroud, b 6.4
Before removing the muffler, set the
piston to top dead center to ensure
that no dirt falls into the cylinder.
: Pry out the plugs (1)
– do not re-use plugs that have
been removed.
: Take out the screws (1).
: Remove the muffler (2), check
and replace if necessary.
– Remove the exhaust gasket
– always install a new exhaust
gasket.
1
2310RA067 TG
1
1
2310RA068 TG
1
2
– Remove and install the spark
arresting screen, if fitted – see
instruction manual.
Installing
– Cover the exhaust port. Remove
any dirt from around the cylinder
and exhaust port.
: Check and clean the sealing
faces (arrows), remove any
gasket residue – make sure there
is no gasket residue or dirt in the
exhaust port.
Always replace components with
damaged sealing faces.
– Position the new exhaust
gasket (1) so that the
tabs (arrows) point towards the
cylinder.
: Fit the new exhaust gasket (1)
and use the tabs (arrows) to line
it up on the cylinder.
2310RA069 TG2310RA070 TG
1
: Carefully place the muffler (1) in
position.
: Check the position of the gasket
and fit the screws (2).
: Insert and tighten down the
screws (2) firmly.
– Use a blunt tool to push home the
new plugs squarely and uniformly
– take care not to damage the
plugs.
2
2310RA071 TG
2
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