Stihl model · engine series 1139
MS 181 31.8 cc
- Chain
- 3/8″ Picco / .325″
- Recommended bar
- 14–18″
- Mount
- 3005 / A074
MS 181 chain size: 3/8″ Picco / .325″, 3005-mount bar. Typical STIHL drive-link counts for 3/8" Picco (low-profile) chain: 14″ = 50, 16″ = 55, 18″ = 61. 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 171 · 181 · 211 family specs · chain and file size guide · part number lookup
Parts diagrams (16)
Browse saved diagrams & other models ↗404 parts entries · catalogue coverage: MS 181, MS 181 C. Check the sheet’s variant and serial notes.
Model & family fitment specs
Displacement is specific to the MS 181 roster record. Chain, bar and mount are the published family fitment for engine series 1139; 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 181
Pitch & gauge 3/8″ Picco / .325″ · recommended bar 14–18″ · bar mount 3005 / A074 · round file 5/32" (4.0 mm)
Chain & bar by length
| Bar | Drive links | Shop |
|---|---|---|
| 14″ | 50 DL | Chain → Bar · 3005 → |
| 16″ | 55 DL | Chain → Bar · 3005 → |
| 18″ | 61 DL | Chain → Bar · 3005 → |
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 3005 / A074; 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 90PX (.043″) / 91PX (.050″). 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 | 13,500 rpm |
| H screw (high speed) | 3/4 turn |
| LA screw (idle stop) | 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 181
31.8 cc; all MS 181s are series 1139 (1139 020 xxxx parts)
Production, market and rarity are specific to this model’s roster record.
Related models in series 1139
Shared engine-family membership does not establish parts interchangeability.
Data confidence
Chain, bar, mount and displacement confidence comes from the shared MS 171 · 181 · 211 family research.
Something wrong or missing for the MS 181? Report a correction →