WhichPartFits.com

Chainsaw

Stihl MS 660

2-Stroke

The Stihl MS 660 is a 91.6cc 2-stroke professional chainsaw and the highest-displacement standard-production model in Stihl's MS lineup. Produced from the late 1990s through the 2010s, it became the benchmark for extreme-duty milling, old-growth felling, and large-diameter rescue cutting. The MS 660 accepts guide bars up to 36" and runs a Walbro HD carburetor demanding meticulous fuel system maintenance at this displacement. Stens and Oregon produce extensive aftermarket parts inventories for the MS 660 given its widespread professional use and long production run. The MS 660 superseded the Stihl 066.

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 660 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, 0000 140 4402, 0000 350 3518, 1122 120 0611, 1122 080 2103, 1122 400 1304, 4238 350 6201, 1124 358 7700
Model Family
MS 660
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 660, 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, 0000 140 4402, 0000 350 3518, 1122 120 0611 and match the removed part before choosing a listing.

Named part options

Cross-check named parts such as NGK BPMR7A (spark plug), Stens 605-672 (air filter), Walbro WJ-66 (carburetor) 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 660 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 660? 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 660? 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

OEM0000 140 4402
Variant notes
HD2 heavy-duty filter; also fits MS 441, MS 461

Fuel Filter

OEM0000 350 3518
Variant notes
Orange in-tank pickup body fuel filter
  • 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

OEM1122 120 0611
Variant notes
Walbro WJ-66; 91.1cc engine — do not substitute WJ-67 or WJ-68

Recoil Starter

OEM1122 080 2103

Ignition Coil

OEM1122 400 1304
  • 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

OEM4238 350 6201
Variant notes
Newer units (SN# 287332321+) use 0000 350 6202

Fuel Line Kit

OEM1124 358 7700
Variant notes
Includes fuel pickup line and return line; fits MS640, MS650, MS660

Chain

OEMSpec-based fitment
Dimensions
25", 3/8" pitch, .063" gauge, 84 drive links
Variant notes
Stock bar length; verify drive link count matches your bar

Guide Bar

OEMSpec-based fitment
Dimensions
25", 3/8" pitch, .063" gauge