MS170 Stihl Chainsaw Manual

The STIHL MS 170 is a lightweight, easy-to-handle chainsaw designed for occasional users and homeowners. It features a powerful gasoline engine, STIHL Quickstop® inertia chain brake, Ematic™ lubrication system, and STIHL ErgoStart™ for easier starting. 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 Lever, Throttle Trigger Lockout, Master Control Lever, Fuel and Oil Tanks.

Feature	Description
Engine	STIHL 2-stroke gasoline engine, air-cooled
Guide Bar	Available in various lengths (e.g., 16")
Saw Chain	STIHL Picco Micro 3 (PM3) chain
Chain Brake	STIHL Quickstop® inertia-activated chain brake
ErgoStart™	Reduces pulling force required for starting
Ematic™ System	Efficient chain lubrication to reduce oil consumption
Master Control Lever	Combines choke, throttle lock, and stop control
Throttle Trigger Lockout	Prevents accidental throttle activation
Fuel Tank Capacity	Approx. 8.5 fl. oz. (0.25 liter)
Oil Tank Capacity	Approx. 5.1 fl. oz. (0.15 liter)

Safety Information

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

1. PPE Requirements: Safety glasses, hearing protection, gloves, chainsaw chaps or pants, sturdy boots.
2. Operating Area: 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 any object.
4. Chain Brake: Test function before each use. Engage when carrying the saw more than a few steps or when not in immediate use.

WARNING! Improper use can cause serious injury or death. Never operate a chainsaw while tired, or under the influence of drugs or alcohol.

Assembly & Preparation

Unpack and inspect contents. Assemble the guide bar and chain.

1. Attach the Guide Bar: Remove the side cover. Place the bar over the studs, ensuring the tensioning pin engages in the bar's hole.
2. Install the Chain: Place the chain over the bar, ensuring cutting teeth face forward on the top of the bar. Fit the drive links into the bar groove.
3. Replace Side Cover: Ensure the chain is correctly seated, then replace and tighten the side cover nuts hand-tight.
4. Tension the Chain: Use the combination wrench to turn the tensioning screw clockwise until the chain fits snugly against the bar but can still be pulled around by hand.
5. Final Tighten: Hold the bar tip up and fully tighten the side cover nuts. Re-check tension.
6. Fill Fluids: Add STIHL 50:1 2-cycle engine oil mixed with gasoline to the fuel tank. Add STIHL chain oil to the oil tank.

CAUTION! Always use the correct fuel/oil mixture. Using straight gasoline will destroy the engine.

Specifications

• Engine Displacement: 30.1 cc
• Power Output: 1.5 kW / 2.0 bhp
• Weight (powerhead only): 6.8 lbs (3.1 kg)
• Fuel/Oil Ratio: 50:1 (STIHL 2-Stroke Oil)
• Recommended Guide Bar Lengths: 12" to 16"
• Chain Pitch/Gauge: 3/8" PM / .043" (1.1 mm)
• Ignition System: STIHL Electronic Ignition (CDI)
• Sound Power Level: 112 dB(A)
• Vibration Levels (left/right): 3.5/4.0 m/s²

Controls and Components

Familiarize yourself with all controls before starting.

Front/Right Side: Muffler, Chain Catcher, Bumper Spike, Guide Bar, Saw Chain.

Top/Handle Area:

• Master Control Lever: Moves between positions: STOP (0), RUN (I), and START/CHOKE (II).
• Throttle Trigger: Controls engine speed. Must be unlocked by the Throttle Trigger Lockout.
• Chain Brake Lever (Front Hand Guard): Push forward manually to engage brake; inertia will engage it automatically upon kickback.
• Combination Wrench: Stored in the handle for bar nuts and tensioning screw.

Left Side: Side Cover, Chain Tensioning Screw, Fuel and Oil Tank Caps.

Starting & Stopping the Engine

Cold Start Procedure:

1. Place saw on firm, level ground. Engage the chain brake by pushing the front hand guard forward.
2. Press the decompression valve (if equipped).
3. Move Master Control Lever to CHOKE position (II).
4. Press the fuel pump bulb (if equipped) at least 5 times until fuel is visible.
5. Grip the rear handle with your right hand and place your right foot in the handle. Pull the starter grip slowly until you feel resistance, then give a strong, brisk pull. Repeat until engine fires (a short pop).
6. Immediately move Master Control Lever to RUN position (I).
7. Pull starter cord again until engine starts.
8. Blip the throttle to disengage the fast idle. The saw is ready when the chain brake is disengaged.

Warm Start: Master Control Lever remains in RUN (I) position.

Stopping: Move Master Control Lever to STOP (0).

Operating the Chainsaw

Proper technique is critical for safety and efficiency.

1. Basic Stance: Stand with feet shoulder-width apart, left foot slightly forward. Hold the front handle with your left hand and the rear handle with your right hand.
2. Making a Cut: Let the saw do the work. Apply light downward pressure. Do not force it. Use the bumper spike to pivot into the wood.
3. Kickback Prevention: Maintain a firm grip. Do not cut with the upper tip of the bar. Be especially cautious when re-entering a previous cut.
4. Chain Lubrication: The Ematic™ system operates automatically. Check oil level frequently and ensure the oiler port on the bar is not clogged.
5. Carrying the Saw: Always engage the chain brake. Hold the saw with the bar pointing behind you.

WARNING! Never operate the chainsaw above shoulder height or with one hand.

Maintenance Schedule

Task	Before Each Use	Weekly / 5 Hours	Monthly / 20 Hours	Annually / 100 Hours
Check chain tension	✓
Check chain sharpness	✓
Inspect chain brake function	✓
Clean air filter		✓
Clean spark arrestor screen			✓
Clean cooling fins			✓
Replace spark plug				✓
Check fuel filter			✓
Check all nuts/bolts	✓

Chain Sharpening & Tensioning

A sharp, properly tensioned chain is essential for safe and efficient operation.

Sharpening:

1. Use a round file matching your chain's pitch (e.g., 4.0mm for PM3). Use a filing guide for consistency.
2. Secure the bar. File each cutter from the inside out, maintaining the original angle (typically 30°).
3. File all cutters to the same length. File depth gauges (rakers) with a flat file and gauge to maintain proper height difference.

Tensioning: Chain should be snug against the bar but pull freely by hand. Tension increases when the chain is hot; always check tension when cold. Loosen side cover nuts, adjust tensioning screw, then retighten nuts.

CAUTION! Always wear heavy gloves when handling the chain.

Storage

For storage longer than 30 days:

1. Drain all fuel from the tank and run the engine until it stops to clear the carburetor.
2. Remove the chain and bar. Clean thoroughly and coat with oil to prevent rust.
3. Clean the entire saw, including the air filter and cooling fins.
4. Store in a dry, cool place, out of reach of children.

Tip: Use STIHL Fuel Stabilizer if you cannot drain the fuel system completely.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, old fuel, flooded engine, clogged filter	Check spark plug. Use fresh fuel mix. Move control to RUN and pull with throttle open. Clean air filter.
Engine starts then dies	Clogged fuel filter, carburetor adjustment, vent hole blocked	Replace fuel filter. Have dealer adjust carburetor. Clean fuel tank cap vent.
Chain does not turn	Chain brake engaged, clutch worn, sprocket worn	Disengage chain brake. Inspect clutch and drive sprocket for wear; replace if necessary.
Chain throws oil excessively	Oil pump setting too high	Adjust oil pump output (consult dealer).
Chain dulls quickly	Cutting dirty wood, hitting ground, improper filing	Avoid cutting into dirt or sand. Sharpen correctly with proper file angle.
Excessive vibration	Loose components, unbalanced chain, damaged AV mounts	Tighten all nuts/bolts. Check chain for damaged/welded links. Inspect anti-vibration mounts.

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

Support: 1-800-467-8445; www.stihlusa.com