Stihl FS 81 Parts Manual

The Stihl FS 81 is a professional-grade brushcutter/trimmer designed for demanding clearing and trimming tasks. This parts manual provides detailed exploded views, part numbers, and ordering information for the FS 81 powerhead, including its engine, drive shaft, cutting attachments, and safety equipment. It is intended for authorized technicians and users performing maintenance and repairs to ensure genuine Stihl parts are used for optimal performance and safety.

1. Introduction & Safety 2. General Specifications 3. Engine Assembly Parts 4. Fuel System Parts 5. Ignition System Parts 6. Drive Shaft & Gearhead Parts 7. Cutting Attachment Parts 8. Handle & Control Parts 9. Fasteners & Hardware 10. Part Number Index 11. Ordering Information

Introduction & Safety

This manual is for reference when ordering replacement parts. Using non-genuine parts may void warranty and compromise safety.

Warning SymbolMeaning
⚠️Indicates a potential hazard that could result in serious injury or death if not avoided.
⚙️Indicates a maintenance point requiring specific tools or procedures.

WARNING! Always disconnect the spark plug boot before performing any maintenance or parts replacement. Use only Stihl-approved parts.

General Specifications

Engine Assembly Parts

Cylinder, piston, crankshaft, crankcase, and associated components.

  1. Cylinder (1104 020 1201): Includes cylinder fins and transfer ports.
  2. Piston Assembly (1104 030 2001): Piston, rings, wrist pin, and circlips.
  3. Crankshaft (1104 040 0600): Complete crankshaft assembly.
  4. Crankcase (1104 050 1000): Upper and lower halves.
  5. Muffler (1104 140 0600): Spark arrestor muffler assembly.

Note: Engine parts must be installed by a qualified technician to ensure proper sealing and timing.

Fuel System Parts

Fuel tank, carburetor, fuel lines, filter, and air filter.

Part DescriptionPart Number
Fuel Tank Assembly1104 350 0500
Carburetor (Zama C1Q-S266)1104 120 0650
Fuel Filter0000 350 3502
Fuel Line (5x7mm)0000 350 0940
Air Filter Element1104 140 1000
Primer Bulb1104 141 0400

Ignition System Parts

Ignition module, spark plug, stop switch, and wiring.

  1. Ignition Module (1104 400 1003): Electronic control unit.
  2. Spark Plug (Bosch WSR6F or equivalent): Electrode gap 0.5mm.
  3. Stop Switch (1104 960 1000): Handle-mounted kill switch.
  4. Spark Plug Boot (1104 970 1000): High-tension lead terminal.

CAUTION! Ensure ignition timing is correctly set after module replacement.

Drive Shaft & Gearhead Parts

Flexible drive shaft, gearhead housing, bevel gears, and bearings.

Cutting Attachment Parts

Parts for PolyCut heads, metal blades, and blade nuts.

  1. PolyCut Head (1104 880 1000): Complete trimmer head assembly.
  2. Trimmer Line (3.0mm): Part number 0000 350 3020.
  3. Metal Cutting Blade (4-tooth): Part number 1104 005 1001.
  4. Blade Nut & Washer (1104 881 1000): Retaining hardware.
  5. Deflector (1104 882 1000): Debris shield.

WARNING! Always use the correct guard and ensure cutting attachments are securely fastened and balanced.

Handle & Control Parts

Loop handle, throttle trigger, throttle cable, and harness.

ComponentPart Number
Loop Handle Assembly1104 170 1000
Throttle Trigger1104 171 1000
Throttle Cable1104 172 1000
Harness Hook (D-ring)1104 173 1000
Handlebar Mounting Clamp1104 174 1000

Fasteners & Hardware

Screws, nuts, washers, and clips specific to the FS 81.

Common hardware includes:

Tip: Always replace fasteners with the exact Stihl part number to ensure proper torque and fit.

Part Number Index

Quick reference for major part numbers.

DescriptionPart Number
Complete Engine Crankcase1104 050 1000
Carburetor Repair Kit1104 120 0651
Starter Assembly (Rewind)1104 130 1000
Drive Shaft Complete1104 790 1001
Gearhead Seal Kit1104 792 1001
Safety Harness (Comfort)1108 790 1000

Ordering Information

Contact an authorized Stihl dealer to order parts. Provide the model (FS 81) and part number.

  1. Locate your nearest dealer at www.stihlusa.com.
  2. Provide the machine's serial number for exact parts matching.
  3. Parts are subject to availability; some may require ordering.
  4. Warranty on genuine Stihl parts is handled through the selling dealer.

Service Support: For technical assistance, contact Stihl Inc. at 1-800-467-8445 or visit the official website.

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