Stihl FS 80 Parts Manual

The Stihl FS 80 is a professional-grade brushcutter/trimmer designed for demanding clearing and trimming tasks. This parts manual provides detailed diagrams, part numbers, and ordering information for all components of the FS 80, including the engine, cutting head, drive shaft, handles, 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.

Introduction & Safety

This manual contains exploded-view diagrams and corresponding parts lists for the Stihl FS 80. Always prioritize safety when servicing power equipment.

Safety Symbol	Meaning
⚠️	Warning - Risk of personal injury or damage
🔧	Note - Special service instruction
⚙️	Torque specification required
🛡️	Use genuine Stihl parts only

WARNING! Disconnect the spark plug boot before performing any maintenance or parts replacement. Use appropriate personal protective equipment (PPE).

Engine Assembly Parts

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

1. Cylinder Group: Includes cylinder, gaskets, and decompression valve.
2. Piston Group: Piston, piston rings, wrist pin, and circlips.
3. Crankshaft Group: Crankshaft, main bearings, and seals.
4. Crankcase Group: Crankcase halves, screws, and dowel pins.

Note: Engine serial number is required for ordering certain matched assemblies.

Drive Shaft & Gearhead Parts

Components transmitting power from the engine to the cutting attachment.

• Drive Shaft: Flexible shaft, upper and lower drive tubes.
• Gearhead Housing: Metal housing, bearing, and seal.
• Output Shaft: Shaft, retaining clip, and washer.
• Bevel Gears: Upper and lower bevel gears with shims for backlash adjustment.

Tip: Lubricate the gearhead with Stihl gear grease after reassembly.

Cutting Attachment Parts

Parts for the trimmer head and blade options.

Part Description	Part Number	Notes
PolyCut Head 25-2	0000 350 4001	Standard bump-feed trimmer head
Circular Grass Blade	0000 350 3020	4-tooth, 230mm diameter
Blade Bolt & Washer	0000 957 0901	M10 x 1.5, includes shoulder washer
Deflector	4118 350 0700	Mandatory safety component

Handle & Control Parts

Loop handle, throttle trigger, lockout, and control cables.

1. Handle Assembly: Loop handle with vibration damping.
2. Throttle Controls: Throttle trigger, lockout lever, and cable.
3. Stop Switch: Ignition kill switch and wiring.
4. Harness Attachments: D-rings and mounting points for harness.

CAUTION! Ensure throttle cable is routed correctly and moves freely without binding after reassembly.

Fuel System Parts

Fuel tank, cap, lines, filter, and carburetor components.

Fuel Tank: HDPE tank, vent, and mounting grommets. Carburetor: C1Q-S series carburetor, diaphragm kit, gaskets, adjustment screws. Fuel Lines: Supply and return lines, primer bulb, and filter.

WARNING! Use only clean, fresh fuel mix (Stihl MotoMix or 50:1 with Stihl HP Ultra oil). Drain tank before parts replacement.

Ignition System Parts

Spark plug, ignition module, flywheel, and stop switch wiring.

1. Disconnect spark plug boot.
2. Remove flywheel cover and fan.
3. Identify ignition module part number (varies by spec).
4. Check air gap between module and flywheel magnets (0.3mm).

Specification: Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5mm.

Air Filter & Cooling Parts

Air filter cover, pre-filter, main filter, and cooling system components.

• Air Filter Set: Felt pre-filter and polyurethane main filter.
• Filter Cover: Plastic cover with latch.
• Cylinder Cover: Metal shroud and deflector.
• Starter Cover: Housing with anti-vibration elements.

Note: Clean air filter regularly. Replace if damaged or excessively dirty.

Starter Assembly Parts

Rewind starter pulley, rope, handle, spring, and housing.

Component	Part Number	Qty
Starter Rope	0000 350 3200	1
Starter Spring	0000 350 2903	1
Starter Pulley	0000 350 2700	1
Starter Handle	0000 350 3105	1

CAUTION! Starter spring is under tension. Wear safety glasses during disassembly/assembly.

Fasteners & Hardware

Screws, nuts, washers, and clips used throughout the unit.

Includes: M5 x 25mm flange screws for crankcase, M6 x 16mm for cylinder, E-clips for shaft retainers, wave washers, and lock nuts. Always replace with identical Stihl fasteners to maintain proper clamping force and vibration resistance.

Tip: Use a torque wrench. Refer to specific torque values in the service manual.

Parts Ordering Guide

How to identify and order correct parts.

Step	Action	Details
1	Locate Model & Serial	Find on engine housing. FS 80, Serial: XXX XXX XXX.
2	Use Exploded Diagram	Identify item number from relevant diagram in this manual.
3	Reference Parts List	Find corresponding part number for the item.
4	Contact Dealer	Provide model, serial, and part number to authorized Stihl dealer.

Support: For technical assistance or to locate a dealer, visit www.stihlusa.com or call 1-800-467-8445.