Stihl FS 80 R Manual

The Stihl FS 80 R is a professional-grade straight-shaft grass trimmer/brushcutter featuring a powerful 2-stroke engine, anti-vibration system, ErgoStart™ for easy starting, a loop handle for comfortable operation, and a modular design compatible with various 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, ErgoStart™, loop handle, throttle trigger with lockout, stop switch, and fuel tank.

Feature	Description
Engine Type	2-stroke, single-cylinder, air-cooled
Displacement	30.1 cm³ (1.84 cu. in.)
Power Output	1.3 kW (1.8 hp)
Fuel System	Diaphragm carburetor
Starting System	ErgoStart™ (recoil starter)
Drive Shaft	Straight, solid
Anti-Vibration	Integrated dampers in handle and shaft
Handle	Loop handle with controls
Cutting Attachment	Accepts trimmer heads and metal blades
Fuel/Oil Mix	50:1 (STIHL HP Ultra 2-stroke oil)

Assembly & Preparation

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

1. Attach the shaft: Connect the drive shaft to the engine unit, ensuring it clicks into place. Secure with the provided clamp.
2. Install the handle: Slide the loop handle onto the shaft at your preferred working height and tighten the screws securely.
3. Attach the cutting tool: Follow section 7 for specific instructions on installing trimmer line heads or blades.
4. Prepare fuel: Mix gasoline (min. 89 octane) with STIHL HP Ultra oil at a 50:1 ratio in an approved fuel can.

WARNING! Always wear appropriate Personal Protective Equipment (PPE): safety glasses, hearing protection, gloves, long pants, and sturdy boots during assembly and operation.

First-Time Operation

Before starting, ensure unit is fully assembled and fuel is prepared.

1. Fuel the unit: Fill the tank with the pre-mixed 50:1 fuel/oil mixture. Avoid spills.
2. Priming: Press the fuel pump bulb (primer) 5-10 times until fuel is visible in the bulb.
3. Choke/Starting: Set the master control lever to the cold start (choke) position. Engage the rear handle lockout and pull the starter rope briskly until the engine fires. Move the lever to the warm start/half-throttle position and pull again to start.
4. Warm-up: Allow the engine to run at idle for 30-60 seconds before applying throttle.

CAUTION! Never start the engine indoors or in poorly ventilated areas. Exhaust gases are toxic.

Specifications

• Model: FS 80 R
• Engine Power: 1.3 kW (1.8 hp)
• Displacement: 30.1 cm³
• Fuel Consumption: Approx. 0.65 L/h
• Sound Power Level: 112 dB(A)
• Vibration Levels (Left/Right): 4.5/5.5 m/s²
• Weight (without cutting tool): 5.9 kg (13.0 lbs)
• Shaft Type: Straight
• Recommended Cutting Tools: Trimmer heads, circular grass blades, brush knives
• Warranty: Refer to your local STIHL warranty statement.

Controls and Settings

Master Control Lever: Combines choke, throttle setting, and stop functions. Throttle Trigger: Located on the rear handle; press to increase engine speed. Handle Lockout: Must be engaged before the throttle trigger can be pressed. Stop Switch: "I" for run, "O" for stop. Throttle Interlock: Prevents accidental throttle activation.

Adjustments: Carburetor idle speed (Screw LA) and high-speed mixture (Screw H) are preset at the factory. Only authorized STIHL dealers should adjust H and L screws.

Attaching Cutting Tools

Ensure the engine is OFF and spark plug boot is disconnected.

1. For Trimmer Heads: Place the correct STIHL trimmer head onto the driveshaft. Hold the shaft and rotate the head clockwise until it clicks and locks. Pull to ensure it's secure.
2. For Metal Blades: Use the appropriate blade washer and retaining nut. Place the blade onto the output shaft, followed by the washer. Screw on the nut and tighten firmly using the supplied combination wrench, holding the shaft stationary.

Tip: Always use the STIHL recommended guard for the specific cutting tool being installed.

Operating Instructions

Supports trimming grass, weeds, and light brush.

1. Starting: Follow First-Time Operation steps.
2. Trimming Technique: Use a smooth, sweeping motion from side to side, keeping the cutting head parallel to the ground. Do not force the tool.
3. Brush Cutting: For thicker material, use a metal blade and employ a "mowing" scythe-like motion.
4. Stopping: Release the throttle trigger and allow the engine to return to idle. Move the master control lever to the STOP (O) position.
5. Line Advance: For bump-feed heads, tap the head firmly on the ground while the engine is at high RPM to advance fresh line.

WARNING! Keep bystanders and pets at least 15 meters away. Be aware of thrown objects. Never operate above shoulder height.

Maintenance Schedule

Air Filter: Clean weekly (more often in dusty conditions); replace when damaged. Spark Plug: Check and clean electrode gap (0.5 mm / 0.020 in) every 50 hours; replace annually. Fuel Filter: Replace every 3 months or as needed. Gear Housing Grease: Lubricate daily via the grease nipple. Spark Arrestor Screen (muffler): Clean every 100 hours.

Care & Storage

After use: Clean the exterior with a damp cloth. Never use a pressure washer. For storage longer than 30 days: 1. Drain the fuel tank and run the carburetor dry. 2. Remove spark plug, add a teaspoon of engine oil into the cylinder, pull starter rope slowly to distribute, then reinstall plug. 3. Store in a clean, dry place, protected from dust and moisture.

CAUTION! Fuel is highly flammable. Store fuel mix in an approved container away from sparks, heat, and open flame.

Regulatory Information

This product complies with relevant EPA and CARB emissions standards for handheld engines. It meets applicable ANSI/OPEI safety standards. The muffler contains a USDA approved spark arrestor. For genuine STIHL parts and service, contact an authorized STIHL servicing dealer. © STIHL Incorporated. STIHL, ErgoStart, and the STIHL logo are trademarks of STIHL.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, bad spark	Check fuel level and mix. Move master control to half-throttle and pull starter repeatedly (clear flood). Check spark plug.
Engine starts then dies	Clogged fuel filter, dirty air filter	Replace fuel filter. Clean air filter.
Loss of power	Clogged spark arrestor, dirty air filter	Clean spark arrestor screen. Clean air filter.
Excessive vibration	Damaged cutting tool, loose parts	Inspect and replace damaged blade or head. Tighten all nuts and bolts.
Cutting tool does not spin	Drive shaft disconnected, clutch worn	Check shaft connection. Have dealer inspect clutch.

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

Support: www.stihlusa.com or consult your local STIHL dealer.