Stihl MS 170 Manual PDF

The Stihl MS 170 is a lightweight, easy-to-handle chainsaw designed for occasional users and homeowners. It features a powerful gasoline engine, low-emission engine technology, STIHL Quickstop® inertia chain brake, easy-start system, tool-free fuel and oil caps, and a side-access chain tensioner. This manual covers safety instructions, assembly, operation, maintenance, troubleshooting, and specifications. Always read and understand the manual before use.

1. Safety Instructions 2. Assembly & Preparation 3. Controls & Components 4. Starting & Stopping 5. Operation & Cutting Techniques 6. Maintenance Schedule 7. Chain Sharpening & Tensioning 8. Fuel & Lubrication 9. Troubleshooting 10. Specifications 11. Warranty & Support

Safety Instructions

Critical safety warnings to prevent injury or death. Always wear protective equipment.

Hazard	Precaution
Kickback	Hold saw firmly with both hands; use reduced-kickback chain; avoid tip contact.
Chain brake	Ensure STIHL Quickstop® is functional; test before each use.
Protective gear	Wear safety glasses, hearing protection, gloves, chainsaw chaps, and sturdy boots.
Fuel handling	Refuel in well-ventilated area with engine off and cool; no smoking.
Working area	Clear debris; ensure secure footing; keep bystanders away.
Electric lines	Assume all lines are energized; stay at least 10 feet away.
Reactive forces	Be prepared for pushback, pull-in, and kickback; maintain control.
Fatigue	Take breaks; do not operate when tired or under influence.

Assembly & Preparation

Unpack and assemble your MS 170 before first use.

Attach guide bar and chain: Place bar on studs, loop chain over sprocket, align with bar groove, tighten nuts.
Fill oil tank: Use STIHL chainsaw oil or equivalent; fill to max mark.
Mix fuel: Use 50:1 mix of unleaded gasoline (min. 89 octane) and STIHL 2-cycle oil. Shake well.
Fill fuel tank: Add mixed fuel to tank; secure cap tightly.
Check chain tension: Chain should snap back when pulled from bar; adjust via side tensioner if needed.

WARNING! Never use straight gasoline; it will destroy the engine. Use proper personal protective equipment (PPE).

Controls & Components

Familiarize yourself with the controls and their functions.

Component	Function
Throttle trigger	Controls engine speed; releases throttle trigger lockout.
Throttle trigger lockout	Must be depressed to operate throttle; safety feature.
Master control lever	Combines stop switch, choke, and start positions.
Chain brake lever	Engages chain brake manually; activates automatically via inertia.
Fuel cap	Tool-free access to fuel tank.
Oil cap	Tool-free access to chain oil tank.
Side chain tensioner	Adjusts chain tension without tools.
Decompression valve	Reduces pulling resistance for easier starting (if equipped).
Front handguard	Protects left hand; part of chain brake system.

Starting & Stopping

Proper starting procedure ensures safe operation.

Cold Start: Place saw on firm ground. Engage chain brake. Set master control to choke (full down). Press decompression valve (if equipped). Pull starter rope sharply until engine fires. Move master control to half-throttle position. Pull again to start. Let engine warm up at idle.
Warm Start: Set master control to run position (horizontal). Pull starter rope.
Stopping: Release throttle; let engine idle. Push master control up to STOP position.

CAUTION! Always engage chain brake when starting or carrying saw. Keep hands away from chain.

Operation & Cutting Techniques

Basic cutting methods for safe and efficient work.

Felling: Plan escape path. Make notch cut (1/3 diameter). Make felling cut opposite notch. Use wedges if needed.
Limbing: Stand uphill; cut from trunk outward. Beware of spring poles.
Bucking: Support log; cut from top side. Avoid pinching chain; use plastic or wooden wedges.
General: Use full throttle when cutting. Let chain do the work; don't force. Maintain secure grip.

Tip: Keep chain sharp; a dull chain increases effort and risk of kickback.

Maintenance Schedule

Regular maintenance ensures performance and longevity.

Interval	Task
Before each use	Check chain tension, sharpness, and brake function; inspect for loose parts.
Daily	Clean air filter; check fuel and oil levels; clean saw exterior.
Weekly	Clean spark arrestor screen (if equipped); inspect spark plug.
Monthly	Clean cooling fins; check fuel filter; inspect anti-vibration elements.
As needed	Sharpen chain; replace worn bar; clean chain oil tank screen.

Chain Sharpening & Tensioning

A properly maintained chain is essential for safety and performance.

Tensioning: Loosen bar nuts. Turn side tensioner screw clockwise to tighten chain. Chain should snap back when pulled from bar. Retighten bar nuts.
Sharpening: Use round file matching chain pitch (typically 3/8" LP). File each cutter at prescribed angle (usually 30°). Maintain equal length on all cutters. File depth gauges with flat file.

WARNING! Always wear gloves when handling chain. Disconnect spark plug wire for safety during maintenance.

Fuel & Lubrication

Use correct fuels and lubricants to avoid damage.

Fuel Mix: 50:1 ratio. Use unleaded gasoline with minimum 89 octane (R+M)/2. Mix with STIHL 2-cycle engine oil. Do not use fuel older than 60 days.
Chain Oil: Use STIHL chainsaw bar and chain oil or equivalent. Check oil flow before cutting.
Storage: For long-term storage, run engine dry of fuel. Store in dry, secure place.

CAUTION! Gasoline is highly flammable. Store fuel in approved container away from sparks or flame.

Troubleshooting

Problem	Possible Cause	Solution
Engine won't start	No fuel; flooded; spark plug faulty; master control position	Check fuel; wait if flooded; check/replace spark plug; ensure correct control setting.
Engine runs poorly	Dirty air filter; old fuel; clogged fuel filter	Clean/replace air filter; use fresh fuel; replace fuel filter.
Chain doesn't turn	Chain brake engaged; clutch worn; sprocket damaged	Disengage brake; inspect clutch and sprocket; replace if needed.
Chain throws oil	Oil tank overfilled; wrong oil viscosity	Fill to correct level; use recommended oil.
Excessive vibration	Loose components; damaged anti-vibration mounts	Tighten all fasteners; inspect mounts.
Chain dulls quickly	Cutting dirty wood; hitting ground; improper filing	Avoid contact with dirt; sharpen correctly.

Specifications

Engine Displacement: 30.1 cc (1.8 cu. in.)
Power Output: 1.5 kW (2.0 bhp)
Fuel Tank Volume: 0.25 L (8.5 fl. oz.)
Oil Tank Volume: 0.15 L (5.1 fl. oz.)
Guide Bar Lengths: 30 cm (12"), 35 cm (14"), 40 cm (16")
Chain Pitch: 3/8" PMM (Picco Micro Mini)
Weight (powerhead): 3.9 kg (8.6 lbs)
Sound Pressure Level: 104 dB(A)
Vibration Level: Left/Right: 3.5 m/s², Front/Rear: 2.5 m/s²
Emissions Compliance: EPA Phase III, CARB Tier III

Warranty & Support

STIHL Limited Warranty: 1 year for homeowner use. Registration may be required. For technical support, parts, or service, contact an authorized STIHL servicing dealer. Always use genuine STIHL replacement parts. For manual downloads, visit www.stihlusa.com.

Service Hotline: 1-800-467-8445 (USA)