STIHL MS 170 Instruction Manual

The STIHL MS 170 is a lightweight, easy-to-handle chainsaw designed for occasional users and homeowners. It features a powerful gasoline engine with STIHL's easy-to-start technology, an anti-vibration system, an inertia chain brake for safety, an automatic chain oiler, and a side-access chain tensioner. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Engine, Guide Bar, Saw Chain, Chain Brake, Throttle Trigger, Master Control Lever, Chain Tensioner, Chain Sprocket, Fuel Tank, Oil Tank.

Safety Information

Read and understand all instructions before use. Always wear proper PPE.

1. Personal Protective Equipment (PPE): Always wear safety glasses, hearing protection, gloves, chainsaw chaps/pants, and sturdy boots.
2. Work Area Safety: Keep bystanders and pets at least 15 feet away. Ensure secure footing.
3. Kickback Zone: Be aware of the upper quadrant of the guide bar tip. Do not let this part contact wood.
4. Chain Brake: Test before each use. Engage when carrying the saw more than a few steps.
5. Fuel Safety: Mix fuel outdoors. Use only STIHL 2-stroke oil and fresh gasoline. Store fuel in approved containers.

WARNING! A chainsaw is a dangerous tool. Failure to follow safety rules can result in serious injury or death.

Assembly & Preparation

Unpack and inspect contents. Assemble on a clean, stable surface.

1. Attach Guide Bar & Chain: Place bar on sprocket. Loop chain onto bar with cutters facing forward on top. Fit bar onto studs and tighten nuts finger-tight.
2. Tension Chain: Use side tensioner screw to raise bar tip. Tighten until chain fits snugly against bar but can be pulled by hand. Final-tighten bar nuts.
3. Fill Fuel Tank: Use proper 50:1 fuel/oil mix (2.6 oz oil per 1 gal gasoline).
4. Fill Oil Tank: Use STIHL chain oil or a quality substitute.
5. Check Chain Brake: Pull front hand guard back toward you; it should click into place. Push forward to disengage.

CAUTION! Ensure chain brake is disengaged before starting.

Specifications

• Engine Displacement: 1.8 cu in (30.1 cc)
• Power Output: 1.5 kW (2.0 bhp)
• Weight (powerhead): 8.6 lbs (3.9 kg)
• Fuel/Oil Ratio: 50:1 (STIHL 2-Stroke Oil)
• Guide Bar Lengths: 14" or 16"
• Chain Pitch/Gauge: 3/8" PM / .043" (1.1 mm)
• Sound Pressure Level: Approx. 104 dB(A)
• Vibration Levels (left/right): Approx. 4.5/5.5 m/s²
• Warranty: Limited warranty for private users. See dealer for details.

Controls and Components

Front/Rear Handles: Ensure firm grip with both hands. Master Control Lever: Controls stop (0), choke (up), and run (down). Throttle Trigger: With safety throttle trigger lockout. Throttle Lockout: Must be depressed to allow throttle trigger movement. Chain Brake Lever/Front Hand Guard: Stops chain if activated. Decompression Valve: Reduces pulling force for starting. Primer Bulb: Press 5+ times to fill carburetor with fuel for cold starts.

Operation: Always engage chain brake before starting. Hold saw firmly on ground. Use correct starting procedure.

Starting & Stopping the Engine

Cold Start:

1. Place saw on firm ground. Engage chain brake.
2. Press primer bulb 5+ times.
3. Set Master Control Lever to choke position (full up).
4. Pull starter rope sharply until engine fires once.
5. Move Master Control Lever to run position (down one click).
6. Pull starter rope again to start engine.
7. Briefly blip throttle to disengage fast idle.

Warm Start: Master Control Lever in run position. No priming needed.

Stopping: Release throttle. Move Master Control Lever to stop position (0).

Basic Operation & Cutting

Always plan your cut and escape path.

1. Basic Stance: Stand with feet shoulder-width apart, left foot slightly forward.
2. Grip: Left hand on front handle, thumb wrapped underneath. Right hand on rear handle, finger on throttle trigger.
3. Starting a Cut: Apply light throttle. Let the chain do the work; do not force.
4. Bucking (cutting felled logs): Support log off ground. Cut from top. Beware of pinch points.
5. Limbing: Work from trunk outward. Keep saw stable; beware of spring-loaded branches.

WARNING! Never operate above shoulder height. Never cut with the tip. Be alert for kickback.

Maintenance Schedule

CAUTION! Perform maintenance only when engine is off and cool. Disconnect spark plug wire for major work.

Chain Sharpening & Tensioning

Sharpening: Use correct round file size (typically 5/32" for PM3 chain). Maintain correct filing angle (30°). File all cutters to equal length. Check depth gauges with gauge tool and file down if necessary.

Tensioning: Loosen bar nuts. Turn side tensioner screw clockwise to tighten until chain fits snugly against bar but can be pulled around by hand. Hold bar tip up and final-tighten bar nuts. Re-check tension after a few minutes of operation.

Tip: A sharp chain cuts faster, is safer, and reduces wear on the saw.

Storage

For storage longer than 30 days:

1. Drain fuel tank and run carburetor dry.
2. Remove chain and bar. Clean and oil them. Store bar flat.
3. Clean entire saw of dirt and sawdust.
4. Store in a dry, secure place, out of reach of children.

CAUTION! Never store a saw with fuel in the tank for extended periods. Old fuel can damage the engine.

Troubleshooting

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

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