Stihl FS 80 Trimmer Manual

The Stihl FS 80 is a professional-grade straight-shaft grass trimmer/brushcutter designed for demanding clearing, trimming, and cutting tasks. It features a powerful 2-stroke engine, anti-vibration system, loop handle with throttle trigger lockout, adjustable harness, 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, Loop handle with controls, Adjustable harness, Anti-vibration system, Quick-stop inertia clutch.

Assembly & Preparation

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

1. Attach the handle: Slide onto shaft, align for operator height, tighten clamping screws securely.
2. Install the harness: Connect harness hooks to attachment points on the machine.
3. Fit the cutting tool: Ensure engine is off. Follow instructions for attaching trimmer head or blade.
4. Fuel mix: Prepare 50:1 gasoline to 2-stroke engine oil mix (use STIHL HP Ultra or equivalent). Fill fuel tank.

WARNING! Always wear protective equipment: safety glasses, gloves, ear protection, long pants, and sturdy boots. Never assemble or fuel near open flames or sparks.

Starting & Stopping

Starting Procedure (Cold Engine):

1. Place unit on clear, flat ground. Engage the throttle trigger lockout.
2. Set ignition switch to ON (I) position.
3. Press and release the decompression valve (if equipped).
4. Set choke lever to full choke position.
5. Press the fuel pump (purge) bulb 5-10 times until fuel is visible.
6. Hold the unit firmly with one hand on the handle and one foot in the rear handle. Pull starter rope briskly until engine fires.
7. Move choke lever to half-choke or run position. Pull starter again to start.
8. Allow engine to warm up at idle for 30 seconds before applying throttle.

Stopping: Release throttle, allow engine to idle, then move ignition switch to STOP (0) position.

Specifications

• Engine Displacement: 30.1 cc (1.84 cu. in.)
• Power Output: 1.3 kW (1.8 hp)
• Fuel/Oil Ratio: 50:1 (Gasoline to 2-stroke oil)
• Fuel Tank Capacity: 0.53 liters (18 fl. oz.)
• Idle Speed: 2,800 rpm
• Maximum Powerhead Speed: 11,500 rpm
• Drive Shaft: Straight, solid
• Gearhead Ratio: 1.27:1
• Sound Pressure Level: Approx. 96 dB(A)
• Vibration Level (Front/Rear Handle): Approx. 4.5/2.5 m/s²
• Weight (Powerhead): 5.9 kg (13.0 lbs)

Controls and Components

Main Controls on Handle: Throttle Trigger, Throttle Trigger Lockout, Ignition Switch (On/Stop).

Other Components: Choke Lever, Decompression Valve, Fuel Pump (Purge) Bulb, Rewind Starter Grip, Carburetor Adjustment Screws (LA - Idle, H - High Speed).

Maintenance Points: Air Filter Cover, Spark Plug, Muffler, Fuel Filter, Gearhead Greasing Nipples.

Attaching Cutting Tools

Ensure engine is OFF and spark plug boot is disconnected.

1. Trimmer Line Head: Hold output shaft with wrench. Rotate head counterclockwise to remove. Install new head by threading clockwise and tightening firmly.
2. Metal Blades (Brush Knife/Circular Saw): Use appropriate blade washer and retaining nut. Tighten nut securely with wrench while holding shaft. Always use correct guard for the blade.
3. Multi-Head Tool System (if equipped): Depress locking buttons, insert tool, and rotate until it clicks into place.

Tip: Always check that the cutting tool is securely fastened and the guard is properly installed before each use.

Operation & Techniques

Proper Use for Trimming and Clearing:

1. Put on all personal protective equipment (PPE). Adjust harness for balanced, comfortable fit.
2. Start engine as described. Allow to warm up.
3. For trimming grass: Use a smooth, sweeping motion from side-to-side, keeping the cutting head parallel to the ground. Cut from right to left for best debris dispersal.
4. For clearing brush: Use a metal blade. Use a swinging, scything motion. Do not force the blade; let the tool do the work.
5. Maintain a firm grip with both hands. Keep solid footing and be aware of your surroundings.
6. Never operate above waist height. Always cut away from your body.

WARNING! Inspect work area for stones, wire, and other debris that could become projectiles. Keep bystanders and pets at least 50 feet away.

Maintenance Schedule

Daily (Before Use): Check for loose fasteners, inspect cutting tool and guard, check fuel system for leaks.

After Each Use: Clean exterior, check air filter, clean debris from cooling fins and guard.

Storage

For storage longer than 30 days:

1. Drain all fuel from the tank and carburetor. Run engine until it stops.
2. Remove spark plug, add 1-2 teaspoons of engine oil into cylinder. Pull starter slowly 2-3 times to coat internals. Reinstall spark plug.
3. Thoroughly clean the entire unit, especially the cooling fins, air filter, and cutting attachment.
4. Store in a dry, clean, and secure place, out of reach of children.

CAUTION! Never store unit with fuel in the tank indoors or in an enclosed space due to fire and fume hazards.

Safety & Warnings

Read and understand the manual completely before operation. This machine can cause serious injury.

• Always wear the provided protective equipment.
• Keep hands and feet away from the cutting attachment at all times.
• The cutting tool continues to rotate after the throttle is released (inertia). Wait for complete stop.
• Never operate the machine when tired, ill, or under the influence of drugs/alcohol.
• Be aware of kickback danger, especially with metal blades.
• Use only STIHL approved cutting attachments and replacement parts.

Troubleshooting

Service: For repairs and major adjustments, contact an authorized STIHL servicing dealer. Use only genuine STIHL parts.

Support: Visit www.stihlusa.com or contact STIHL customer service.