Stihl 031 AV Chainsaw
Lawn · lawn
The Stihl 031 AV is a professional-grade 2-cycle chainsaw used for tree work, limb removal, brush clearing, and any cutting the trimmer blade cannot handle. It is the most dangerous power tool on the truck. Read every safety item on this page before each use — no exceptions.
This page covers the equipment profile. The full workshop manual (Stihl 031/032) is available in My Manuals & Links below.
Quick Reference
- Engine: 2-cycle, 54.6 cc
- Fuel: PREMIUM 91+ at 50:1 ratio
- Chain oil: Bar & chain oil (automatic oiler)
- Bar length: 16–20 in (confirm with shop)
- Weight (bare): ~11.7 lb without bar/chain
- Required PPE: Chainsaw chaps, face shield, hearing protection, gloves, steel-toe boots
- Kickback zone: Bar tip — never use tip to start a cut
- Clearance zone: NO ONE within 50 ft while cutting
Full Specs
Specifications for the Stihl 031 AV chainsaw. Confirm bar length and chain pitch with the shop before replacing any chain components.
Stihl 031 AV — Specifications
| Spec | Value |
|---|---|
| Engine type | 2-cycle, single cylinder |
| Displacement | 54.6 cc |
| Power output | ~3.2 hp |
| Fuel | PREMIUM 91+ at 50:1 ratio — same shop standard as all 2-cycle tools |
| Mix ratio | 50:1 (2.6 oz JASO FD or ISO-L-EGD rated 2-cycle oil per gallon) |
| Oil brand | Stihl HP Ultra preferred; shop-approved JASO FD equivalent acceptable |
| Bar length | 16–20 in (confirm installed bar with shop) |
| Chain oil | Bar & chain oil — dedicated chainsaw bar oil ONLY; do not substitute |
| Chain oiler | Automatic (manual primer bulb) |
| Weight (bare) | ~11.7 lb without bar and chain |
| Anti-vibration | Yes — AV-mounted engine/handle system |
| Chain brake | Inertia-activated front hand guard |
Fuel & Oil
The 031 AV uses two fluids: the 50:1 premix in the fuel tank, and bar-and-chain oil in the oil tank. Both must be checked before every use. Never confuse the two tanks — the oil cap and fuel cap are color-coded on most Stihl units (fuel = typically colored cap, oil = typically black cap).
- Fuel: PREMIUM 91+ at 50:1 ratio — 2.6 oz JASO FD or ISO-L-EGD 2-cycle oil per gallon
- Confirm the fuel can label says "MIX 50:1 — PREMIUM" with a date before fueling
- Fuel under 30 days old; add stabilizer if tool will sit >2 weeks
- Bar-and-chain oil tank: fill with dedicated bar oil — DO NOT substitute with motor oil, hydraulic oil, or vegetable oil
- Never run the saw without bar oil — dry chain destroys the bar groove and chain drive links in minutes
- Pre-mixed cans (TruFuel 50:1, VP Small Engine Fuel) are approved and preferred when the saw will sit between jobs
- Never use E15 or E85; E10 maximum if non-ethanol unavailable
Before Each Use
Run this check before every start. A chainsaw in poor condition creates the conditions for a kickback, bar pinch, or chain-throw incident.
- PPE on before touching the saw: chainsaw chaps, face shield (not just glasses), hearing protection, snug-fitting gloves, steel-toe or composite-toe boots, long sleeves
- Fuel level — check fuel cap label reads "MIX 50:1 — PREMIUM"; confirm fuel in tank
- Bar-and-chain oil level — oil tank visible through inspection window or via cap; fill if low
- Chain tension — chain should not sag below the bar but should pull smoothly by hand (with saw off and brake set); adjust per manual if tight or loose
- Chain brake — push the front hand guard forward; chain should lock immediately; release by pulling guard back toward handle
- Chain condition — no cracked or broken links, no missing cutters, all cutters at equal length; dull or damaged chain is out
- Bar — no cracks, bent rail, or damaged tip; bar rail groove clean of debris
- All guards in place — top hand guard, chain catcher, bar tip guard (if applicable)
- Throttle trigger and interlock — trigger must not move without pressing the interlock first; confirm spring return works
- Work area clear — no bystanders within 50 ft; stable footing; no overhead hazard
Safety — Read Before Every Use
The chainsaw presents two primary hazards: kickback and bar pinch. Kickback happens when the tip of the bar contacts an object or gets pinched, throwing the bar upward toward the operator at speed. Bar pinch happens when the material closes on the bar mid-cut. Both can be fatal. The items below are non-negotiable.
- PPE is mandatory and non-optional: chainsaw chaps (or pants with chainsaw cut-resistance), full face shield, hearing protection, snug-fitting gloves, steel-toe boots, long sleeves
- Chain brake must function — test before every use: push front guard forward, chain must stop immediately
- Two-handed grip at ALL times — right hand on rear handle, left hand on front handle; thumbs wrapped around handles
- Kickback zone: the upper quadrant of the bar tip — NEVER use the tip to start a bore cut or contact anything with the tip
- Clearance: NO ONE within 50 ft while cutting — stop the engine if anyone enters the area
- Stable footing before every cut — never reach, never lean, never stand on an unstable surface
- Never cut above shoulder height
- Release the trigger if you need to move more than one step — the chain brake is not a substitute for a stopped chain
- Watch for spring-loaded wood — bound material can snap when the cut releases; plan an escape route before starting each cut
- Never cut with a dull chain — dull chain causes the saw to wander, requires forcing, and increases kickback probability
- No alcohol, no medication that causes drowsiness — chainsaw work requires full attention and fast reaction
Kickback Warning — Non-Negotiable
- Kickback is caused by contact at the bar tip or bar pinch — both can throw the bar up at the operator in under 0.1 seconds
- NEVER start a cut with the bar tip; NEVER let the tip contact logs, branches, or the ground
- If the bar feels pinched or bound, stop the engine — do not force the saw free with the chain running
- The chain brake reduces kickback severity but does not prevent it — proper technique is the first line of defense
Maintenance Schedule
Log hours and tasks in the job tracking app. Never skip chain sharpening — a dull chain is the leading cause of kickback.
Service Intervals — Stihl 031 AV
| Interval | Task |
|---|---|
| Each use | Check chain tension and sharpness; inspect chain brake; fill bar oil and fuel; clear bar groove of debris |
| Every 5 hrs | Sharpen chain (or when saw starts pulling to one side, cutting slowly, or leaving rough cuts); clean air filter; clean bar groove |
| Every 25 hrs | Replace air filter if clogged or torn; clean spark arrestor screen; inspect bar for wear and flip bar (wear both rails evenly) |
| Every 50 hrs | Replace spark plug; inspect fuel lines and filter; check clutch for glazing or wear; inspect all fasteners |
| Every 100 hrs | Replace air filter assembly; replace fuel filter; inspect chain drive sprocket and replace if hooked or worn; inspect oil pump output |
| Seasonal / Annual | Drain fuel or run dry; fog cylinder with storage oil; clean and lightly oil bar and chain; store in case or hung up, not on floor |
Troubleshooting
Common chainsaw issues and field fixes. Never operate a chainsaw with a known safety defect.
Stihl 031 AV — Field Troubleshooting
| Symptom | Likely Cause | Field Fix | Stop & Call Shop If |
|---|---|---|---|
| Won't start | Stale fuel, fouled plug, wrong choke sequence, flooded | Drain stale mix; refill fresh PREMIUM 50:1; full choke on cold start; half choke once it pops. If flooded: choke open, throttle at low, pull through repeatedly. | Fresh mix, clean plug, correct sequence — still won't fire after 3 sets of pulls |
| Chain doesn't stop when brake engaged | Chain brake worn, contaminated with oil, or cable stretched | Do not operate — chain brake failure is a disqualifying defect | Immediately — do not use saw until inspected |
| Chain doesn't stop within 5 sec of trigger release | Clutch drag or worn clutch springs | Stop use | Shop inspection required before next use |
| Bar overheating / chain smoking | Low bar oil, clogged oil port, wrong oil type | Check oil tank and port; clear port with wire if clogged; use only proper bar-and-chain oil | Oil tank full, port clear — still smoking after 1 minute of normal cutting |
| Bogging under load / sluggish cut | Dull chain, clogged air filter, spark arrestor fouled, stale fuel | Sharpen or replace chain; clean air filter; clean spark arrestor screen; drain and refill fresh mix | Fresh fuel, clean filter, sharp chain — still bogs. Carb diaphragm service needed. |
| Runs rough at idle / won't idle | Idle mixture screw, air leak, dirty carb | Let dealer service carb — do not adjust mixture screws in the field | Shop service |
| Excessive vibration | Loose bar nuts, worn anti-vibration mounts, bent bar | Check and tighten bar nuts to spec; inspect bar for bend | Anti-vibration mounts worn — shop inspection |