Manual for Stihl MS 170

The Stihl MS 170 is a lightweight, compact chainsaw designed for homeowners and occasional users. It features a powerful gasoline engine with easy-start technology, an anti-vibration system, an inertia-activated chain brake for safety, a side-access chain tensioner, and a tool-free fuel and oil cap system. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Engine with Easy2Start™ system, guide bar, saw chain, chain brake, side-access chain tensioner, combined choke/stop control, and anti-vibration handles.

Assembly & Preparation

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

1. Attach the guide bar and chain: Place bar on mounting studs, loop chain around bar with cutting edges facing forward, adjust tension via side knob.
2. Fill with fuel: Use STIHL MotoMix® pre-mixed fuel or mix 50:1 with STIHL 2-stroke oil and 89+ octane gasoline.
3. Fill chain oil: Use STIHL chain oil or approved alternative in separate oil tank.
4. Check chain lubrication: Run saw briefly and inspect for oil on chain/bar.

WARNING! Always wear appropriate PPE: safety glasses, gloves, hearing protection, chainsaw chaps, and sturdy boots. Never operate without proper training.

First-Time Operation

Perform pre-start checks before each use.

1. Check chain tension: Chain should be snug against bar but pull freely by hand.
2. Check chain sharpness: Dull chains increase kickback risk and reduce efficiency.
3. Start the saw: Place on ground, engage chain brake, set master control lever to cold start position (choke), pull starter rope until engine fires, then move lever to run position and pull again to start.
4. Warm up: Allow engine to idle for 30 seconds before cutting.
5. Test chain brake: With engine at idle, activate brake by pushing front hand guard forward; chain should stop immediately.

CAUTION! Keep bystanders and pets at least 15 feet away. Plan your cut and escape path before starting.

Specifications

• Engine Displacement: 30.1 cc (1.84 cu. in.)
• Power Output: 1.5 kW (2.0 bhp)
• Fuel Tank Volume: 250 ml (8.5 fl. oz.)
• Oil Tank Volume: 145 ml (4.9 fl. oz.)
• Guide Bar Lengths (Option): 16" (standard), 14" or 18" available
• Chain Pitch: 3/8" PMM3
• Weight (Powerhead): 3.9 kg (8.6 lbs)
• Sound Pressure Level: 104 dB(A)
• Vibration Level (Front/Rear): 4.5/2.5 m/s²
• Warranty: Limited 2-year consumer warranty

Controls and Functions

Master Control Lever: Combines choke, run, and stop positions. Throttle Trigger: Controls engine speed. Throttle Trigger Lockout: Must be depressed to engage throttle. Chain Brake Lever: Manual activation via front hand guard. Chain Catcher: Helps reduce risk if chain breaks. Side-Access Chain Tensioner: Knob for adjusting chain tension.

Starting Procedure: Engage chain brake. Set master control to cold start (choke). Pull starter rope until engine fires. Move lever to run position. Pull starter rope again to start. Disengage chain brake before cutting.

Chain & Bar Maintenance

Proper maintenance ensures safety and performance.

1. Chain Sharpening: Use round file and guide; maintain correct filing angle (30°). Sharpen when chips become dust-like.
2. Chain Tension: Adjust when chain sags from bar or is too tight to pull. Adjust via side knob with engine off and cool.
3. Bar Maintenance: Clean bar groove regularly; flip bar periodically for even wear.
4. Sprocket: Inspect for wear; replace if teeth are hooked or worn.

Tip: Always wear heavy gloves when handling the chain. Keep chain sharp – a sharp chain is safer than a dull one.

Fuel & Lubrication

Use only high-quality, fresh fuel and lubricants.

1. Fuel Mix: 50:1 ratio (2% oil) with 89+ octane gasoline and STIHL 2-stroke oil. STIHL MotoMix® recommended for optimal performance and storage.
2. Chain Oil: Use STIHL chain oil or approved biodegradable alternative. Check oil flow regularly.
3. Refueling: Stop engine and allow to cool. Clean area around caps. Fill tanks on level surface.
4. Storage: For long-term storage, run engine dry or use fuel stabilizer.

WARNING! Fuel is highly flammable. No smoking. Refuel outdoors away from ignition sources. Wipe up spills immediately.

Safety Features

Chain Brake: Stops chain within milliseconds if activated manually or by inertia during kickback. Throttle Trigger Lockout: Prevents accidental throttle engagement. Right-Hand Guard: Protects hand from chain. Chain Catcher: Helps contain broken chain. Anti-Vibration System: Reduces fatigue and improves control.

Care & Storage

Clean saw after each use. Remove debris from air intake, cooling fins, and guide bar. Check all fasteners for tightness. Store in dry, secure location out of reach of children. For seasonal storage: Clean thoroughly, empty fuel tank or add stabilizer, run engine dry, remove chain and store in oil.

CAUTION! Never use pressure washers or solvents. Do not store with fuel in tank for extended periods without stabilizer.

Regulatory Information

EPA and CARB certified for emissions. Meets ANSI B175.1 safety standards. Contains parts from global suppliers. Copyright © STIHL Incorporated. All rights reserved. For genuine parts and accessories, visit an authorized STIHL dealer. For support, contact STIHL USA at 1-800-467-8445 or visit www.stihlusa.com.

Troubleshooting

Service: For repairs beyond basic maintenance, take to authorized STIHL dealer. Use only STIHL genuine parts.

Emergency: In case of injury or fire, call local emergency services first.