Stihl model · engine series 1140
MS 391 64.1 cc
- Chain
- 3/8″ · .050–.063″
- Recommended bar
- 16–25″
- Mount
- 3003 / D025
MS 391 chain size: 3/8″ · .050–.063″, 3003-mount bar. Typical STIHL drive-link counts for 3/8" (full) chain: 16″ = 60, 18″ = 66, 20″ = 72, 22″ = 76, 25″ = 84. Count the links on your old chain or read the bar stamp before ordering.
Model displacement · family chain/bar fitment. Details & confidence ↓
See also: MS 362 · 311/391 · MS 400 family specs · chain and file size guide · part number lookup
Parts diagrams (13)
Browse saved diagrams & other models ↗302 parts entries · catalogue coverage: MS 391. Check the sheet’s variant and serial notes.
Model & family fitment specs
Displacement is specific to the MS 391 roster record. Chain, bar and mount are the published family fitment for engine series 1140; confirm the pitch, gauge and drive-link count stamped on your installed bar before ordering.
Chain, bar and mount: family research from STIHL product pages and parts catalogues, dealer fiche and collector records. Checked Jul 2026. How we check fitment
Chains & bars that fit the MS 391
Pitch & gauge 3/8″ · .050–.063″ · recommended bar 16–25″ · bar mount 3003 / D025 · round file 7/32" (5.5 mm) for Oregon; STIHL lists 13/64" (5.2 mm)
Chain & bar by length
| Bar | Drive links | Shop |
|---|---|---|
| 16″ | 60 DL | Chain .050″ →Chain .063″ → Bar · 3003 → |
| 18″ | 66 DL | Chain .050″ →Chain .063″ → Bar · 3003 → |
| 20″ | 72 DL | Chain .050″ →Chain .063″ → Bar · 3003 → |
| 22″ | 76 DL | Chain .050″ →Chain .063″ → Bar · 3003 → |
| 25″ | 84 DL | Chain .050″ →Chain .063″ → Bar · 3003 → |
Drive-link counts come from STIHL's saw-chain selection chart and depend on the bar mount as well as length. Pick the chain link that matches the gauge stamped on your bar. Bar searches include mount 3003 / D025; still confirm the mount stamp, pitch, gauge and drive-link count on your installed bar before ordering.
Drive-link counts: STIHL 2025 US catalog, saw chain selection, pp. 166-167; Oregon chain fit guide, STIHL section. Checked Nov 2026. How we check fitment
Files, oil & sharpening
Suggested match: Oregon 72 (.050″) / 73 (.058″) / 75 (.063″) series, e.g. 72/75 EXL. Match the gauge and confirm the drive-link count for your exact bar before ordering. These are equivalent aftermarket (Oregon) chains, not genuine STIHL chain — STIHL sells its own chain through its dealer network, and we're not affiliated with STIHL. New to fitment? See the bar-mount identification guide and chain & cutter guide.
Some links earn us a commission. It never changes the specs or what we recommend.
Service & tuning
Factory tuning settings
| Idle speed | 2,800 rpm |
| Max speed | 13,000 rpm |
| H screw (high speed) | 3/4 turn |
| LA screw (idle stop) | 1 1/2 turns |
| Confidence | sourced |
Screw figures are turns open from lightly seated. Set the final mixture by ear and tachometer against the machine in front of you — running a two-stroke lean to hit a published number is how pistons get scored.
About the MS 391
Farm & Ranch, 64.1 cc
Production, market and rarity are specific to this model’s roster record.
Related models in series 1140
Shared engine-family membership does not establish parts interchangeability.
Data confidence
Chain, bar, mount and displacement confidence comes from the shared MS 362 · 311/391 · MS 400 family research.
Something wrong or missing for the MS 391? Report a correction →