Stihl 031 Chainsaw Manual

The Stihl 031 is a professional-grade gasoline-powered chainsaw designed for demanding cutting tasks. It features a robust engine, automatic chain oiling, anti-vibration system, and a range of safety features. Below are key sections covering safety, features, operation, maintenance, troubleshooting, and specifications.

1. Safety Instructions 2. Features at a Glance 3. Assembly & Preparation 4. Starting & Stopping 5. Operation & Cutting Techniques 6. Maintenance Schedule 7. Chain & Bar Care 8. Carburetor Adjustment 9. Troubleshooting 10. Specifications 11. Warranty & Support

Safety Instructions

Read and understand all instructions before operating the Stihl 031 chainsaw. Failure to follow safety rules may result in serious injury or death.

Hazard	Precaution
Kickback	Always hold saw firmly with both hands; use reduced-kickback chain; do not saw with tip.
Hearing damage	Wear approved hearing protection during operation.
Eye injury	Always wear safety glasses or face shield.
Fire/Explosion	Refuel in well-ventilated area with engine off and cool. Wipe off spilled fuel.
Carbon Monoxide	Operate only in well-ventilated areas.
Vibration	Take regular breaks to reduce risk of Hand-Arm Vibration Syndrome (HAVS).

WARNING! Never operate a chainsaw when fatigued, under the influence of drugs/alcohol, or in adverse weather conditions.

Features at a Glance

Key components: Engine, Fuel Tank, Oil Tank, Chain Brake, Throttle Trigger, Throttle Lockout, Choke Control, Decompression Valve, Muffler, Chain Catcher.

Feature	Description
Engine Displacement	51.5 cc (3.14 cu. in.)
Power Output	3.0 bhp
Fuel Tank Capacity	0.55 US pt (0.26 l)
Oil Tank Capacity	0.42 US pt (0.20 l)
Guide Bar Lengths	16" to 20" (40 cm to 50 cm)
Chain Pitch	3/8" or .325"
Ignition System	Electronic, breakerless
Anti-Vibration System	Yes
Automatic Oiling	Yes, with manual override
Weight (without bar & chain)	12.8 lbs (5.8 kg)

Assembly & Preparation

Unpack and inspect contents. Assemble guide bar and chain.

Mount Guide Bar: Place bar on studs, align tensioning pin with hole.
Install Chain: Ensure cutting teeth face forward on top of bar. Fit chain over sprocket and onto bar rails.
Tighten Bar Nuts: Hand-tighten only.
Adjust Chain Tension: Lift tip of bar, turn tensioning screw until chain fits snug against bar but can be pulled by hand. Retighten bar nuts.
Fill Tanks: Use STIHL 2-cycle engine oil mixed 50:1 with unleaded gasoline (min. 89 octane). Fill chain oil tank with STIHL chain oil or equivalent.

CAUTION! Always wear protective gloves when handling the chain. Chain is extremely sharp.

Starting & Stopping

Starting Procedure (Cold Engine):

Place saw on firm, flat ground. Engage chain brake.
Set Master Control Lever to CHOKE position (full down).
Press decompression valve (if equipped).
Pump primer bulb (if equipped) 5-6 times until fuel is visible.
Hold front handle with left hand, place right foot in rear handle. Pull starter rope briskly until engine fires (usually 2-5 pulls).
Move Master Control Lever to FAST IDLE position (half up). Pull starter rope again to start.
Allow engine to warm up. Squeeze throttle trigger to return to idle.

Stopping: Release throttle, allow engine to idle. Push Master Control Lever to STOP position.

Operation & Cutting Techniques

Basic Cutting:

Felling: Plan escape path. Make notch cut (1/3 of tree diameter), then felling cut. Use wedges if needed.
Limbing: Cut branches from bottom to top, using saw as support.
Bucking: Support log. Cut from top down. Beware of pinch points.

Kickback Zone: Avoid contacting the upper quadrant of the guide bar tip with wood.

Tip: Let the saw do the work; do not force it. Maintain a sharp chain.

Maintenance Schedule

Interval	Task
Daily	Check chain tension, sharpness, and lubrication. Clean air filter. Check for loose fasteners.
Every 10 hours	Clean spark arrestor screen (muffler).
Every 20 hours	Clean cooling fins. Check spark plug.
Every 50 hours	Replace fuel filter. Clean carburetor air passage.
Annually	Replace spark plug. Clean fuel tank. Have professional check ignition timing and compression.

WARNING! Perform maintenance only when engine is off and cool. Disconnect spark plug wire.

Chain & Bar Care

Sharpening: Use round file matching chain pitch (e.g., 5/32" for 3/8" chain). File at 30° angle. File all cutters to equal length. Check depth gauges with gauge tool and file down if necessary.

Bar Maintenance: Clean bar groove weekly. Flip bar weekly for even wear. Lubricate sprocket nose.

CAUTION! A dull chain increases kickback risk and operator fatigue.

Carburetor Adjustment

Factory settings are usually correct. Adjust only if necessary (poor performance, excessive smoke).

Start and warm up engine for 5 minutes.
Adjust idle speed (LA screw): Turn until chain just stops moving, then 1/4 turn counter-clockwise.
Adjust low-speed mixture (L screw): For smoothest idle and quick acceleration.
Adjust high-speed mixture (H screw): For maximum power without 4-stroking at full throttle under load. Do not lean out excessively.

Note: H and L screws have limited adjustment range. Tampering may violate emissions regulations.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, stale fuel, clogged filter	Check spark plug; use fresh fuel mix; clean air filter; set choke correctly.
Engine starts then dies	Clogged fuel filter, carburetor issues	Replace fuel filter; clean carburetor screen; adjust carburetor.
Loss of power	Dirty air filter, clogged spark arrestor, dull chain	Clean/replace air filter; clean spark arrestor screen; sharpen chain.
Chain does not oil	Empty oil tank, clogged oil passages	Fill tank; clean oil holes in bar; check oil pump.
Excessive vibration	Loose parts, damaged anti-vibration mounts	Tighten all fasteners; inspect AV mounts.
Chain throws off bar	Loose bar nuts, worn bar, improper tension	Tighten bar nuts; inspect bar for wear; adjust chain tension correctly.

Specifications

Model: STIHL 031 AV
Engine Type: Single cylinder, 2-stroke, air-cooled
Bore x Stroke: 47 mm x 37 mm
Idle Speed: 2,800 rpm
Max. Engine Speed: 12,500 rpm
Fuel/Oil Ratio: 50:1 (STIHL HP Ultra or equivalent)
Spark Plug: Bosch WSR6F or Champion RCJ-6Y (Gap: 0.020")
Sound Pressure Level: 106 dB(A) (approx.)
Sound Power Level: 121 dB(A) (approx.)
Vibration Level (front/rear): 4.5/2.5 m/s² (approx.)
Warranty: Limited 1-year commercial, 2-year residential

Warranty & Support

STIHL Limited Warranty: Defects in material or workmanship for specified period from date of retail purchase. Proof of purchase required. This warranty does not cover normal wear, misuse, neglect, or improper maintenance.

For service, use only STIHL-approved replacement parts. Contact an authorized STIHL servicing dealer.

Support: For dealer locator and manuals: www.stihlusa.com or contact STIHL Incorporated at 1-800-GO-STIHL (1-800-467-8445).