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Chainsaw

Stihl MS 251

2-Stroke

The Stihl MS 251 is a 45.6cc 2-stroke chainsaw and the direct successor to the MS 250, updated with a more fuel-efficient engine, improved anti-vibration, and current emission standards. It accepts 16" to 18" guide bars and occupies the same homeowner/prosumer position. Unlike the MS 250, the MS 251 does not share a carburetor with the MS 210/230 family — it runs its own Zama variant. Routine maintenance items are the air filter, spark plug, fuel lines, and primer bulb. The MS 251 is the recommended current-production choice over the MS 250 generation.

Verify before ordering: Fitment can vary by serial number, production date, region, and sub-model. Match the OEM number and physical dimensions before ordering.

Stihl MS 251 quick specs

Equipment
Chainsaw · 2-Stroke
Covered Parts
Spark Plug, Air Filter, Fuel Filter, Carburetor, Recoil Starter, Ignition Coil, Primer Bulb, Fuel Line Kit, Chain, Guide Bar
OEM References
0000 400 7000, 1143 120 1300, 0000 350 3518, 1143 120 0611, 1143 080 2103, 1143 400 1310, 1143 350 6200, 1143 358 7700
Model Family
MS 210, MS 230, MS 250, MS 251
Data Confidence
Not yet independently reviewed

Quick Fitment

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Tune-Up Kit

Common service bundle: spark plug, air filter, fuel filter, carburetor, primer bulb, fuel line kit.

Maintenance Interval

Inspect filters and fuel lines each season, replace spark plugs during annual service, and service carb/fuel-system parts when starting or idle symptoms appear.

Before You Buy

  • Confirm the full model is Stihl MS 251, not just the family name.
  • Check serial number, production date, and regional variant before ordering.
  • Match the old OEM number stamped on the removed part when available.
  • Compare dimensions, plug gap, thread, fuel line diameter, or chain pitch/gauge where applicable.

Common Mistakes

  • Ordering from a family listing without checking the exact sub-model.
  • Buying a kit that includes the headline part but wrong gaskets, lines, or bulb size.
  • Choosing the wrong carburetor revision when multiple versions were used.
  • Assuming all fuel line kits use the same diameter and routing.
  • Installing the correct plug number with the wrong gap.
  • Matching bar length but missing pitch, gauge, or drive-link count.

Symptoms Map

Won't start

Spark plug, fuel filter, primer bulb, carburetor

Starts then dies

Fuel filter, fuel line kit, carburetor

Bogs under throttle

Air filter, carburetor, spark plug gap

Primer will not fill

Primer bulb, fuel line routing, in-tank filter

Cuts slowly

Chain pitch/gauge, bar wear, drive links

Replacement Options

Best OEM equivalent

Start with OEM references 0000 400 7000, 1143 120 1300, 0000 350 3518, 1143 120 0611 and match the removed part before choosing a listing.

Named part options

Cross-check named parts such as NGK BPMR7A (spark plug), Zama C1Q-S295D (carburetor), Zama BG-00-4 (primer bulb) against the OEM number, identity label, and dimensions.

Best for annual tune-up

Bundle spark plug, air filter, fuel filter when servicing the Stihl MS 251 at the start of the season.

Best if replacing fuel system

Compare the fuel filter, carburetor, primer bulb, fuel line kit together so line routing, bulb size, filter style, and carburetor connections match.

Best chain/bar combo

Match chain specs together, especially pitch, gauge, drive links, and bar mount details.

Best budget kit

Use kit listings only when every included part matches this model page; cheap kits often mix correct headline parts with wrong bulbs, lines, or gaskets.

FAQ

Should I buy OEM or aftermarket parts for the Stihl MS 251? Use OEM when the part controls fuel metering, ignition, or safety. Aftermarket kits can be useful for routine filters, bulbs, plugs, and tune-up bundles when the OEM number and dimensions match.

How do I avoid ordering the wrong carburetor for the MS 251? Match the carburetor number stamped on the removed unit, then compare linkage, choke setup, primer routing, gasket stack, and fuel-inlet direction.

What should I check before replacing fuel-system parts? Photograph the old fuel-line routing, match line diameter and filter style, and compare primer bulb size before buying a kit.

What chain details matter besides bar length? Match pitch, gauge, and drive-link count against the bar stamp, old chain, and drive sprocket. Bar length alone is not enough.

As an Amazon Associate, WhichPartFits earns from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.

Spark Plug

OEM0000 400 7000
Dimensions
0.5mm gap

Air Filter

OEM1143 120 1300
Variant notes
Fits MS 231, MS 251
  • No named part listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Fuel Filter

OEM0000 350 3518
Variant notes
In-tank pickup body fuel filter; updated version for MS 231, MS 251
  • No named part listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Carburetor

OEM1143 120 0611
Variant notes
Zama C1Q-S295D IntelliCarb compensating carburetor; fits MS 231, MS 251

Recoil Starter

OEM1143 080 2103
Variant notes
Fits MS 231, MS 251
  • No named part listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Ignition Coil

OEM1143 400 1310
Variant notes
Fits MS 231, MS 251
  • No named part listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Primer Bulb

OEM1143 350 6200
Variant notes
Fits MS 231, MS 251

Fuel Line Kit

OEM1143 358 7700
Variant notes
Fuel hose for MS 231, MS 251
  • No named part listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Chain

OEMSpec-based fitment
Dimensions
18", .325" pitch, .050" gauge, 68 drive links
Variant notes
Stock bar length; verify drive link count matches your bar

Guide Bar

OEMSpec-based fitment
Dimensions
18", .325" pitch, .050" gauge