Stihl FS 45 Instruction Manual

The Stihl FS 45 is a lightweight, easy-to-handle gasoline-powered string trimmer designed for residential use. It features a curved shaft, a reliable 2-stroke engine with STIHL anti-vibration system, a semi-automatic Tap-n-Go™ line advance system, a translucent fuel tank, and a loop handle for comfortable operation. 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 Functions 6. Fuel & Lubrication 7. Operating Instructions 8. Maintenance & Storage 10. Safety Information 11. Warranty & Support 12. Troubleshooting

Features at a Glance

Key components: 2-stroke engine, Curved shaft, Loop handle, Tap-n-Go™ cutting head, Translucent fuel tank, Throttle trigger lockout, Anti-vibration system.

Feature	Description
Engine	STIHL 2-stroke, air-cooled, single-cylinder
Shaft	Curved, steel drive shaft
Handle	Loop handle with throttle trigger and lockout
Cutting Head	Semi-automatic Tap-n-Go™ line advance
Fuel Tank	Translucent for easy fuel level check
Anti-Vibration	STIHL system reduces operator fatigue
Starter	Rewind starter with easy-grip handle
Weight	Lightweight design for easy handling
Spark Plug	Bosch or NGK, easily accessible
Air Filter	Foam element for engine protection

Assembly & Preparation

Unpack all parts and inspect for damage. Assembly requires attaching the handle, cutting head, and installing the shoulder strap.

Attach Handle: Align handle with shaft, secure with provided bolts and nuts.
Install Cutting Head: Thread the Tap-n-Go™ head onto the drive shaft clockwise until hand-tight.
Install Shoulder Strap: Attach strap hooks to designated rings on the trimmer.
Fill Fuel: Use STIHL MotoMix® or a 50:1 mixture of gasoline and STIHL 2-stroke oil.

WARNING! Always wear protective equipment: safety glasses, gloves, long pants, and sturdy shoes. Assemble on a clean, flat surface.

First-Time Operation

Before starting, ensure all assembly steps are complete and fuel is properly mixed.

Priming: Press the fuel pump bulb (if equipped) 5-10 times until fuel is visible.
Choke: Set choke lever to cold start position (full choke).
Starting: Place trimmer on ground, hold handle firmly, pull starter rope briskly until engine fires.
Warm-up: Move choke to run position, allow engine to idle for 30 seconds.

CAUTION! Keep bystanders and pets at least 50 feet away during operation. Never operate in enclosed spaces.

Specifications

Engine Displacement: 27.2 cc
Power Output: 0.9 kW (1.2 bhp)
Fuel/Oil Ratio: 50:1 (STIHL 2-stroke oil)
Fuel Tank Capacity: 0.42 liters (14.2 fl. oz.)
Cutting Swath: Approx. 430 mm (17 inches)
Drive: Steel drive shaft
Weight (without cutter): Approx. 5.0 kg (11.0 lbs)
Sound Pressure Level: Approx. 96 dB(A)
Vibration Level: Left/Right Handle: Approx. 4.5/6.5 m/s²

Controls and Functions

Main controls located on the loop handle. Throttle Trigger: Controls engine speed. Throttle Trigger Lockout: Must be depressed to engage throttle. Stop Switch: Moves to STOP position to shut off engine. Choke Lever: For cold starting (positions: RUN, START). Fuel Pump Bulb: Primes carburetor (if equipped). Tap-n-Go™ Head: Tap on ground while running to advance cutting line.

Operation: Hold trimmer with right hand on throttle handle, left hand on auxiliary handle. Use shoulder strap to distribute weight.

Fuel & Lubrication

Use fresh, unleaded gasoline with a minimum octane rating of 89. Mix with STIHL 2-stroke engine oil at a 50:1 ratio. For convenience and engine protection, use STIHL MotoMix® pre-mixed fuel.

Always mix fuel in a clean, approved container.
Add oil first, then gasoline. Shake well.
Fill fuel tank outdoors, away from ignition sources.
Lubricate drive shaft splines periodically with STIHL grease.

Tip: Never use fuel older than 30 days. Empty fuel tank before long-term storage.

Operating Instructions

For trimming grass and light weeds.

Starting: Follow First-Time Operation steps.
Trimming Technique: Hold cutting head parallel to ground, 2-3 inches above soil. Swing trimmer in an arc from right to left.
Line Advance: While engine is at high speed, tap cutting head firmly on ground to advance fresh line.
Edging: Tilt trimmer so cutting line is vertical for edging along sidewalks.
Shutdown: Release throttle, allow engine to idle for 30 seconds, move stop switch to STOP.

WARNING! Never operate without proper guard installed. Keep cutting head clear of hard objects like rocks, fences, and buildings.

Maintenance & Storage

Regular maintenance ensures long life and safe operation.

Daily: Clean exterior, check for loose fasteners, inspect cutting head and line.
Weekly: Clean air filter (foam), check spark plug.
Monthly: Grease drive shaft splines, inspect fuel lines.
Storage: Empty fuel tank, run engine until it stops. Remove spark plug, add a teaspoon of oil, pull starter slowly to coat cylinder. Store in a dry, locked place.

CAUTION! Always disconnect spark plug wire before performing any maintenance.

Safety Information

Read and understand manual before use. Always wear: Eye protection, Hearing protection, Gloves, Long pants, Sturdy boots. Keep bystanders away. Be aware of thrown objects. Never operate near flammable materials. Use only STIHL-approved replacement parts.

Warranty & Support

STIHL Limited Warranty: Covers defects in material and workmanship for a specified period from date of retail purchase. Warranty is valid only when purchased from an authorized STIHL dealer. For service, repairs, or genuine parts, contact your local authorized STIHL dealer. For support, visit www.stihlusa.com or contact STIHL Incorporated at 1-800-467-8445.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, bad spark	Check fuel; set choke to RUN, pull starter repeatedly; check spark plug.
Engine runs poorly/dies	Dirty air filter, old fuel	Clean/replace air filter; drain and replace with fresh fuel mix.
Line does not advance	Empty spool, tangled line	Refill spool with correct diameter line; disassemble head to remove tangle.
Excessive vibration	Loose parts, bent shaft	Tighten all bolts/nuts; inspect shaft for damage.
Loss of power	Clogged muffler, carburetor issues	Clean spark arrestor screen; have dealer service carburetor.

Dealer Service: For complex repairs, contact your authorized STIHL dealer.

Support: 1-800-467-8445; www.stihlusa.com