Stihl model · engine series 1139
MS 171 31.8 cc
30.1 cc (Ø 37 mm) and 31.8 cc (Ø 38 mm) — the catalogue lists both cylinders
The production, market and rarity details above are specific to the MS 171 roster record. The displacement below is specific to this roster record. The 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.
Model & family fitment specs
Chains & bars that fit the MS 171
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 → |
Drive-link counts come from STIHL's saw-chain catalog. Bar searches include mount 3005 / A074; still confirm the mount stamp, pitch, gauge and drive-link count on your installed bar before ordering.
Files, oil & sharpening
Suggested match: Oregon 90/91-series (e.g. 91PX). Confirm the drive-link count for your exact bar length 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.
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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.
Parts diagrams (13)
289 part numbers. The catalogue files these under the MS 171, MS 171 C, one bill of material covering this model.
Related models in series 1139
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 171? Report a correction →