Stihl FS 85 Trimmer Manual

The Stihl FS 85 is a professional-grade, straight-shaft grass trimmer/brushcutter designed for demanding clearing and trimming tasks. It features a powerful 2-stroke engine, anti-vibration system, ergonomic handles, a loop handle for control, a translucent fuel tank, a semi-automatic choke, and a robust cutting head system. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Assembly & Preparation 3. First-Time Operation 4. Specifications 5. Controls and Settings 6. Attaching Cutting Tools 7. Operating Procedures 8. Maintenance Schedule 10. Care & Storage 11. Regulatory Information 12. Troubleshooting

Features at a Glance

Key components: 2-stroke engine, Anti-Vibration System (AVS), Ergonomic loop handle, Translucent fuel tank, Semi-automatic choke (Decompression valve), Easy2Start system, QuickStop inertia clutch, Tap-and-go cutting head.

Feature	Description
Engine	Powerful 2-stroke, air-cooled engine
Anti-Vibration System (AVS)	Reduces operator fatigue
Loop Handle	Ergonomic design for better control
Translucent Fuel Tank	Allows for easy fuel level checks
Semi-Automatic Choke	Simplifies cold starting
Easy2Start	Reduces pulling force for starting
QuickStop Inertia Clutch	Stops cutting tool quickly when throttle released
Cutting Head	Tap-and-go line advance system
Drive Shaft	Straight, solid shaft for durability
Throttle Trigger	With throttle trigger lockout for safety

Assembly & Preparation

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

Attach the handle: Align the handle with the shaft and secure with the provided bolts.
Install the cutting tool or guard: Follow instructions for specific trimmer head or blade.
Fuel mix: Prepare a 50:1 mixture of unleaded gasoline (min. 89 octane) and STIHL 2-stroke engine oil.
Fill the fuel tank: Use the fuel mix. Fill the chain oil tank (if applicable for brushcutter blade).

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

First-Time Operation

Perform a safety check before starting.

Starting the engine: Place unit on clear ground. Set master control lever to cold start position (choke on). Press the fuel pump bulb 5 times. Pull starter rope until engine fires. Move master control to run position. Pull starter rope to start.
Warm-up: Allow engine to idle for 30 seconds before applying throttle.
Stopping: Release throttle and allow engine to idle. Move master control lever to STOP position.

CAUTION! Never start the engine in an enclosed area. Exhaust fumes are dangerous.

Specifications

Engine Type: STIHL 2-stroke, single cylinder.
Displacement: Approx. 31.8 cc.
Power Output: Approx. 1.3 kW (1.8 hp).
Fuel/Oil Mix: 50:1 (STIHL 2-Stroke Oil).
Fuel Tank Capacity: Approx. 0.53 liters.
Sound Pressure Level: Approx. 99 dB(A).
Vibration Levels: Front/Rear handle approx. 4.5/2.5 m/s².
Weight (without cutting tool): Approx. 6.2 kg.
Shaft Type: Straight solid shaft.
Recommended Cutting Tools: Trimmer head, grass blade, brush knife.

Controls and Settings

Master Control Lever: Choke/Start/Run/Stop positions. Throttle Trigger: Controls engine speed. Throttle Trigger Lockout: Must be depressed to engage throttle. Stop Switch: Emergency stop. Decompression Valve: Eases starting by reducing cylinder pressure.

Adjustments: Handle can be rotated for user preference. Harness hooks provided for use with STIHL harnesses to reduce operator fatigue.

Attaching Cutting Tools

Ensure engine is OFF and spark plug boot is disconnected.

Remove the cutting attachment guard (if installed).
Use the appropriate STIHL tool holder or blade carrier.
For trimmer head: Thread on clockwise and secure with the retaining plate.
For circular blades: Use the correct flange and nut. Tighten securely with the combination wrench.
Reinstall the correct guard for the cutting tool being used.

Tip: Always use the STIHL recommended guard for each cutting tool.

Operating Procedures

Maintain a firm grip with both hands. Use a harness for extended operation.

Trimming Technique: Hold trimmer head parallel to ground. Use a sweeping motion from side to side.
Brush Cutting: Use a blade. Swing the tool like a sickle in an arc, keeping it away from your body.
Line Advance (Tap-and-Go): Gently tap the cutting head on the ground while at full throttle to advance line.
Avoiding Kickback: Do not use the blade tip or corner. Be aware of the rotating cutting plane.

WARNING! Never operate the tool without the proper guard installed. Clear the work area of bystanders, pets, and debris.

Maintenance Schedule

Air Filter: Clean weekly (more often in dusty conditions). Spark Plug: Check/clean every 50 operating hours, replace as needed. Fuel Filter: Replace annually. Spark Arrestor Screen: Clean every 100 hours. Gear Housing Grease: Lubricate daily via grease nipple. Cutting Tool: Inspect for damage before each use, sharpen/replace blades as needed.

Care & Storage

After use: Clean exterior with a damp cloth. Never use pressure washers. Storage: For long-term storage (over 30 days), drain the fuel tank and run the engine until it stops to prevent fuel system damage. Store in a dry, secure place.

CAUTION! Store fuel mix in an approved container away from heat and ignition sources.

Regulatory Information

Complies with relevant ANSI/OPEI standards and EPA emissions regulations. This product contains chemicals known to cause cancer and birth defects or other reproductive harm (California Prop 65). For genuine STIHL parts and service, contact an authorized STIHL servicing dealer. © STIHL Incorporated. STIHL is a registered trademark.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, spark plug	Check fuel level. Set master control to run, pull starter 10+ times. Check/clean spark plug.
Engine runs poorly/dies	Clogged air filter, fuel filter, carburetor	Clean air filter. Replace fuel filter. Have carburetor serviced by dealer.
Excessive vibration	Damaged cutting tool, loose parts	Inspect and replace damaged blade or trimmer head. Tighten all bolts/nuts.
Line does not advance	Empty spool, tangled line	Refill spool with correct diameter line. Remove spool and untangle line.
Loss of power	Clogged spark arrestor, exhaust port	Clean spark arrestor screen. Have dealer check for carbon buildup in exhaust.

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

Support: Find your local dealer at www.stihlusa.com