Stihl MS 251 Manual

56 MS 231, MS 231 C, MS 251, MS 251 C
Check the flywheel:
– Have pole shoes turned blue?
– Install new flywheel if necessary,
b 7.6
Air gap:
– Check ignition module/flywheel,
– reset if necessary, b 7.3
Check the ignition lead:
– Severe chafing?
– Spark plug boot: Holes/cracks?
– Resistance: spark plug boot to ground:
spec. 1.5 – 12 kΩ
– Check resistance of ignition lead (spark plug
boot and ignition module removed)
Spec.: < 10 Ω,
If necessary, install new spark plug boot and/or
ignition module,
b 7.5
Check short circuit wire:
– Wire damaged?
– Connectors firmly seated?
– Check continuity, replace wiring harness if
necessary, b 7.7.1
1
3
yes
no
2
Powerful
spark?
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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