STIHL FS45 Parts Manual

The STIHL FS45 is a lightweight, straight-shaft grass trimmer designed for residential and commercial use. This parts manual provides detailed diagrams, part numbers, and descriptions for all components of the FS45 trimmer, including the engine, drive shaft, cutting head, handle assembly, and fuel system. It is intended for authorized service technicians and users performing maintenance or repairs. Below are key sections for identification, engine parts, drive system, cutting attachments, controls, and ordering information.

1. Machine Identification & Specifications 2. Engine Assembly & Components 3. Fuel System Parts 4. Ignition & Electrical System 5. Drive Shaft & Gearbox 6. Cutting Attachment Parts 7. Handle & Control Assembly 8. Shaft & Housing Components 9. Fasteners, Decals & Miscellaneous 10. Exploded Views & Diagrams 11. Parts Ordering & Warranty

Machine Identification & Specifications

Locate the model number and serial number on the machine's identification plate. Key specifications for the STIHL FS45.

Feature	Description
Engine Type	STIHL 2-MIX engine, single-cylinder, air-cooled, 2-stroke
Displacement	27.2 cm³ (1.66 cu. in.)
Power Output	0.9 kW (1.2 bhp)
Fuel/Oil Mix	50:1 (STIHL HP Ultra oil recommended)
Shaft Type	Straight solid drive shaft
Cutting Attachment	Standard: STIHL PolyCut head; Optional: Circular grass blade
Weight (without cutting attachment)	Approx. 5.2 kg (11.5 lbs)
Handle System	Loop handle with integrated controls
Anti-Vibration System	Standard
Warranty	STIHL Limited Warranty applies

Engine Assembly & Components

Cylinder, piston, crankshaft, carburetor, and associated parts.

Cylinder & Piston Assembly: Includes cylinder, piston, piston rings, wrist pin, and circlips.
Crankcase & Crankshaft: Crankcase halves, crankshaft, main bearings, seals.
Carburetor Assembly: Complete carburetor, gaskets, throttle linkage, fuel lines.
Muffler & Exhaust: Spark arrestor muffler, gasket, heat shield.
Recoil Starter: Starter assembly, rope, pulley, spring, housing.

WARNING! Engine components are precision parts. Use proper tools and torque specifications during assembly.

Fuel System Parts

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

Fuel Tank Assembly: Tank, cap with vent, mounting brackets.
Fuel Filter & Lines: In-tank filter, fuel hose, primer bulb (if equipped).
Carburetor Parts: Diaphragm kits, needle valve, jets, adjustment screws.
Air Filter System: Air filter element, cover, pre-cleaner.

CAUTION! Use only STIHL-approved fuel lines and filters. Ensure all connections are secure to prevent leaks.

Ignition & Electrical System

Ignition Module: Electronic ignition unit (coil), spark plug boot.
Spark Plug: STIHL-approved type (e.g., BOSCH WSR6F).
Stop Switch: Wire harness, switch assembly, ground wire.
Wiring Harness: Connects stop switch to ignition module.
Flywheel & Magneto: Flywheel with magnets, key, fan blades.

Drive Shaft & Gearbox

Transmits power from engine to cutting attachment.

Drive Shaft: Solid steel shaft, flexible coupling at engine end.

Gearbox Assembly: Bevel gear housing, gears, seals, bearings, grease. Output Shaft: Spindle for attaching cutting head or blade. Clutch: Centrifugal clutch assembly, springs, shoes. Shaft Housing: Aluminum tube, mounting points, anti-vibration elements.

Cutting Attachment Parts

Standard PolyCut head and optional blade parts.

PolyCut Head: Head housing, spool, eyelet, bump knob, spring.
Cutting Line: STIHL monofilament line (specific diameter).
Grass Blade: Circular metal blade, blade bolt, washer, guard.
Blade Adapter: Required for mounting blade to gearbox.
Deflector & Guard: Shield assembly for operator safety.

Tip: Always use the correct guard for the cutting attachment. Inspect blades for damage before use.

Handle & Control Assembly

Loop handle with throttle trigger, lockout, and controls.

Handle Assembly: Loop handle, mounting clamp, vibration dampeners.
Throttle Control: Trigger, cable, throttle lever on carburetor.
Throttle Lockout: Safety lever that must be engaged to operate throttle.
Handle Grip: Rubber grip, retaining screws.
Carrying Harness Attachment Points: D-rings or hooks on handle.

WARNING! Ensure throttle cable is properly routed and adjusted. Test safety lockout function regularly.

Shaft & Housing Components

Main shaft tube, couplings, and anti-vibration mounts.

Fasteners, Decals & Miscellaneous

Screws, nuts, washers, clips, and identification decals.

CAUTION! Use only STIHL genuine fasteners. Incorrect fasteners can lead to component failure.

Exploded Views & Diagrams

Reference diagrams showing part relationships and assembly order. Diagrams are keyed with part numbers corresponding to the parts list. Sections include: Engine Exploded View, Fuel System, Drive Train, Cutting Attachment, Handle Assembly.

Parts Ordering & Warranty

Step	Action	Notes
1. Identify Part	Use exploded view and part number from manual.	Verify model (FS45) and serial number.
2. Contact Dealer	Provide part number to authorized STIHL dealer.	Dealer can check availability and price.
3. Warranty Check	Determine if part is under STIHL warranty.	Warranty may cover defects in materials/workmanship.
4. Installation	Have part installed by qualified technician.	Improper installation can void warranty.
5. Record Keeping	Keep receipt and record of service.	Required for warranty claims.

Support: Contact an authorized STIHL service dealer. For dealer locator or information, visit www.stihlusa.com.

Safety Notice: Use only STIHL original parts. Non-genuine parts can compromise safety, performance, and warranty.