Stihl FS120 Strimmer Manual

The Stihl FS120 is a professional-grade, straight-shaft petrol-powered brushcutter/strimmer designed for demanding vegetation management. It features a powerful 2-stroke engine, anti-vibration system, loop handle with throttle trigger lockout, quick-stop inertia chain brake, and compatibility with a wide range of cutting heads and blades. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 2-stroke engine, straight drive shaft, anti-vibration system, loop handle, throttle trigger with lockout, quick-stop inertia chain brake, and fuel tank.

Safety Instructions

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

1. Personal Protective Equipment (PPE): Always wear safety glasses, hearing protection, sturdy gloves, long pants, and boots.
2. Clear Work Area: Remove stones, nails, wire, and other debris that could be thrown.
3. Fuel Safety: Refuel outdoors only, with engine stopped and cool. Use clean, fresh fuel mix.
4. Operation Zone: Keep bystanders and pets at least 15 meters away.
5. Transport: Carry unit with the cutting attachment covered and the engine stopped.

WARNING! The cutting tool continues to rotate after the throttle is released. Never operate without proper guards in place. Risk of severe injury or death from blade contact or thrown objects.

Assembly & Preparation

Unpack and inspect all parts. Assemble on a clean, flat surface.

1. Attach the Shaft: Insert the drive shaft into the engine housing and secure with the provided bolts.
2. Install the Handle: Slide the loop handle onto the shaft at your preferred working height and tighten the clamping screws securely.
3. Fit the Harness: Connect the shoulder harness to the attachment points on the unit. Adjust for a comfortable, balanced fit.
4. Install Cutting Attachment: Fit the chosen guard first, then attach the cutting head or blade using the appropriate tool and lock nut. Ensure it is securely fastened.
5. Fuel Mix: Prepare a 50:1 mixture of unleaded petrol (min. 90 RON) and STIHL 2-stroke engine oil. Fill the fuel tank.

CAUTION! Ensure all fasteners are tight before starting. Use only STIHL-approved attachments and accessories.

Specifications

• Model: FS 120
• Engine Power: 1.3 kW / 1.7 bhp
• Displacement: 30.1 cm³
• Fuel Tank Volume: 0.55 litres
• Powerhead Weight (without cutting attachment): 6.0 kg
• Sound Pressure Level (LpA): 99 dB(A)
• Sound Power Level (LWA): 112 dB(A)
• Vibration Level (ah): Front Handle: 4.5 m/s², Rear Handle: 6.5 m/s²
• Warranty: Refer to your local STIHL warranty terms.

Controls and Components

Familiarize yourself with all controls before starting.

Main Components: 1. Throttle trigger, 2. Throttle trigger lockout, 3. Stop switch (I/O), 4. Choke lever, 5. Decompression valve, 6. Rewind starter grip, 7. Fuel tank cap, 8. Primer bulb, 9. Inertia chain brake handle/guard, 10. Shaft attachment point, 11. Handle clamping screws.

Operation: The lockout must be depressed before the throttle trigger can be squeezed. The stop switch moves to "I" for ON and "O" for OFF. The inertia brake is activated by a sharp forward motion of the handle; to reset, pull the handle back towards the rear grip.

Starting & Stopping the Engine

Ensure unit is on clear, level ground with cutting attachment clear of obstacles.

1. Cold Start: Set stop switch to "I". Press fuel primer bulb 5 times. Move choke lever to closed position. Depress lockout and briefly open throttle trigger once. Place foot in the rear handle. Pull starter rope briskly until engine fires. Move choke lever to open position. Pull starter rope again to start. Allow brief warm-up at idle.
2. Warm Start: Choke lever must be in open position. Follow steps above without priming.
3. Stopping: Release throttle trigger. Allow engine to idle briefly. Move stop switch to "O".

Tip: Do not pull starter rope to its full extent or let go of the grip while rope is extended.

Operating Instructions

Always maintain a firm, two-handed grip. Use a controlled, sweeping motion.

1. Carrying: Use the provided harness. Adjust so the unit hangs comfortably with the cutting attachment clear of the ground.
2. Swing Technique: Swing the cutting head/blade in an arc from right to left (for right-handed users) in front of you, keeping it parallel to the ground. Let the tool do the work; do not force it.
3. Cutting Height: For grass, aim to cut the top 1/3. For thicker weeds or brush, use a slower, more deliberate swing.
4. Slopes: Always work across the slope, not up and down. Maintain secure footing.
5. Kickback Zone: Be aware that the tip of the cutting attachment (12 o'clock position) is a kickback zone. Avoid contacting solid objects with this area.

WARNING! Never operate the unit above waist height or with one hand. Always be aware of your footing and the swing path.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity. Perform with engine off and cool.

Storage

Prepare the unit properly for storage to prevent fuel system issues.

1. Short-term (up to 4 weeks): Simply empty the fuel tank and run the engine until it stops.
2. Long-term: Empty fuel tank completely. Start engine and run until it stops to clear carburetor. Remove spark plug, add 1-2 teaspoons of engine oil into cylinder, pull starter slowly 2-3 times to coat internals, reinstall plug. Clean entire unit. Store in a dry, secure place, out of reach of children.

CAUTION! Never store the unit with fuel in the tank for long periods. Fuel degrades and can damage the carburetor.

Warranty Information

This STIHL product is covered by a warranty against defects in material and workmanship. The specific terms and duration of the warranty are provided by your local STIHL dealer and may vary by region. Proof of purchase from an authorized STIHL dealer is required for all warranty service. For warranty claims or service, contact the STIHL dealer from whom you purchased the product. For product support and to find a dealer, visit www.stihl.com.

Troubleshooting

Note: For repairs beyond basic maintenance (e.g., carburetor, ignition, internal engine), contact an authorized STIHL servicing dealer.

Service & Support: www.stihl.com