Stihl MS 251 Manual

9MS 231, MS 231 C, MS 251, MS 251 C
3.2 Chain Drive, Chain Brake, Chain Tensioner
Condition Cause Remedy
Chain sprocket wears rapidly Chain not properly tensioned Tension chain as specified
Wrong chain pitch Fit chain of correct pitch
Insufficient chain lubrication Check chain lubrication
Saw chain stops under full load Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Brake band blocked Check freedom of movement and
operation of brake band
Saw chain rotates at idle speed Engine idle speed too high Readjust idle speed screw LA
Clutch springs stretched Replace the clutch springs or install
new clutch
Clutch springs broken Replace the clutch springs
Saw chain does not stop
immediately when brake is
activated
Brake spring stretched or broken Fit new brake spring
Brake band stretched or worn Fit new brake band
Clutch drum worn Install new clutch drum
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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