Stihl MS171 Chainsaw Manual

The Stihl MS171 is a lightweight, easy-to-handle chainsaw designed for occasional users and homeowners. It features a powerful gasoline engine with STIHL's innovative engine and exhaust technology, an anti-vibration system, a QuickStop® inertia chain brake, an Ematic™ lubrication system, a side-access chain tensioner, and a tool-free fuel and oil cap design. Below are key sections for safety, features, operation, maintenance, troubleshooting, and specifications.

Features at a Glance

Key components: Engine with STIHL engine technology, anti-vibration system, QuickStop® inertia chain brake, side-access chain tensioner, Ematic™ lubrication system, and easy-to-use controls.

Safety Information

Read and understand all instructions before operation. Always wear proper Personal Protective Equipment (PPE).

1. PPE Requirements: Safety glasses, hearing protection, gloves, chainsaw chaps or pants, and sturdy boots.
2. Work Area Safety: Keep bystanders and pets at least 15 feet away. Ensure secure footing.
3. Chain Brake Check: Test the inertia chain brake before each use by giving the front hand guard a sharp push forward.
4. Fuel Safety: Refuel in a well-ventilated area, with engine off and cool. Use STIHL MotoMix® or a 50:1 gasoline/oil mixture.

WARNING! Kickback can occur without warning. Always hold saw firmly with both hands. Do not operate above shoulder height or with one hand.

Assembly & First Use

Unpack and inspect contents. Assemble guide bar and chain.

1. Attach Guide Bar & Chain: Place bar on studs, loop chain over sprocket and onto bar groove, ensuring cutting teeth face forward on top. Tighten nuts finger-tight.
2. Tension Chain: Using side-access tensioner, turn screw until chain fits snugly against bar but can be pulled around by hand. Retighten bar nuts.
3. Fill Fluids: Add STIHL 2-stroke engine oil to fuel (50:1 ratio) into fuel tank. Fill bar & chain oil tank with STIHL chain oil.
4. Primer Bulb: Press primer bulb (if equipped) 5-10 times until fuel is visible.

CAUTION! Ensure chain brake is disengaged (pulled back toward rear handle) before starting.

Specifications

• Engine Type: Single cylinder, 2-stroke, air-cooled.
• Displacement: 30.1 cm³ (1.84 cu. in.)
• Power Output: 1.3 kW (1.8 bhp) at 12,500 rpm.
• Idle Speed: 2,800 rpm.
• Max. Engine Speed: 13,500 rpm.
• Fuel/Oil Ratio: 50:1 (using STIHL 2-stroke oil).
• Ignition System: Electronic, capacitor discharge.
• Spark Plug: Bosch WSR 6 F or equivalent.
• Sound Pressure Level: Approx. 104 dB(A).
• Vibration Level (left/right): Approx. 4.5/4.5 m/s².

Controls and Components

Master Control Lever: Combines stop switch, choke, and throttle interlock. Front Hand Guard: Activates chain brake. Throttle Trigger: Controls engine speed. Throttle Trigger Interlock: Must be depressed to engage throttle. Chain Brake Lever: Manual activation/deactivation. Decompression Valve (if equipped): Eases starting. Fuel & Oil Caps: Tool-free design. Chain Tensioner: Side-access screw.

Maintenance Points: Air filter cover, spark plug, chain catcher, muffler.

Starting & Stopping the Engine

Cold Start:

1. Engage chain brake (push hand guard forward).
2. Set Master Control Lever to choke position (full down).
3. Press decompression valve (if equipped).
4. Place saw on ground, hold rear handle with right foot, grip front handle with left hand.
5. Pull starter rope sharply until engine 'fires' (usually 2-5 pulls).
6. Move Master Control Lever to half-throttle position (mid-notch).
7. Pull starter rope again until engine starts.
8. Briefly blip throttle to disengage fast idle. Disengage chain brake before cutting.

Warm Start: Master Control Lever in run position (horizontal). No choke needed.

Stopping: Release throttle, move Master Control Lever up to STOP position.

Operation & Cutting Techniques

Always use full throttle when cutting. Let the chain do the work; do not force it.

1. Felling (Cutting down a tree): Plan escape path. Make notch cut (1/3 tree diameter) on fall side. Make felling cut from opposite side, leaving hinge wood.
2. Limbing: Cut branches from bottom to top, using the saw's bumper spike for leverage. Beware of spring-loaded branches.
3. Bucking (Cutting felled tree): Support log off ground. Cut from top down for most logs. For tensioned logs, cut from compression side first.
4. Kickback Prevention: Keep nose of bar out of cut. Maintain firm grip. Use reduced-kickback chain and bar.

Tip: Regularly check chain tension, especially during first tank of fuel, as new chain stretches.

Maintenance Schedule

CAUTION! Disconnect spark plug wire before performing maintenance other than chain tensioning.

Chain Sharpening & Replacement

Use a round file matching chain pitch (typically 3/8" Picco). Maintain correct filing angle (usually 30°).

1. Secure bar in a vise.
2. Place file guide on chain. File from inside out, using consistent strokes.
3. File all cutters on one side to same length, then turn saw around and file other side.
4. Check depth gauges with a flat file and gauge tool; lower if necessary.
5. For replacement, ensure new chain matches bar pitch, gauge, and drive link count.

WARNING! A dull or damaged chain increases kickback risk and wear. Replace if damaged or excessively worn.

Storage

For storage longer than 30 days:

1. Drain fuel tank and run engine until it stops to clear carburetor.
2. Remove chain, clean it and the guide bar, and coat with oil.
3. Clean entire saw, especially cooling fins and air filter.
4. Store in a dry, secure place, out of reach of children.

CAUTION! Never store with fuel in the tank for extended periods. Use fuel stabilizer if necessary.

Troubleshooting

Service: For repairs beyond basic maintenance, contact an authorized STIHL servicing dealer.

Support: Visit www.stihlusa.com or contact your local STIHL dealer.