STIHL F545 Manual

The STIHL F545 is a professional-grade, high-performance trimmer designed for demanding clearing and trimming applications. It features a powerful 2-stroke engine, robust cutting head options, advanced anti-vibration system, and ergonomic design for extended use. Below are key sections for safety, features, operation, maintenance, troubleshooting, and specifications.

Features at a Glance

Key components: Powerful 2-stroke engine, Ergonomic harness, Anti-vibration system, QuickStop® inertia chain brake, Tool-free cutting head change system, and heavy-duty drive shaft.

Feature	Description
Engine Type	2-stroke, single cylinder, air-cooled
Displacement	45.6 cc
Power Output	High torque for demanding vegetation
Fuel System	Diaphragm carburetor with purge bulb
Ignition System	Electronic, capacitor discharge (CDI)
Anti-Vibration	Advanced damping system in handle and shaft
Cutting Attachments	Accepts various trimmer heads and blades
Drive System	Heavy-duty flexible drive shaft
Starter	STIHL ErgoStart for easy pulling
Weight (without cutting attachment)	Approximately 13.2 lbs (6.0 kg)

Safety Instructions

Read and understand all instructions before use. Always wear appropriate PPE.

1. Personal Protective Equipment (PPE): Always wear safety glasses, hearing protection, heavy-duty gloves, long pants, and sturdy boots.
2. Operating Area: Keep bystanders, especially children and pets, at least 50 feet away.
3. Fuel Safety: Refuel outdoors only, with engine off and cool. Use approved fuel containers.
4. Operation: Hold unit firmly with both hands. Be aware of kickback zone. Do not operate on unstable surfaces.
5. Maintenance: Disconnect spark plug boot before performing any maintenance.

WARNING! Failure to follow safety instructions can result in serious injury or death. This is a powerful tool, not a toy.

Assembly & Preparation

Unpack all parts. Assembly requires attaching the handle, cutting attachment, and harness.

1. Handle Attachment: Slide handle onto shaft at desired position. Tighten clamping screws securely.
2. Cutting Attachment: Ensure drive shaft is clean. Align attachment with drive stud and rotate until it clicks into place. Pull to ensure it is locked.
3. Harness: Adjust harness straps for a snug, balanced fit. The unit should hang comfortably with your arms slightly bent.
4. Fuel Mix: Prepare fuel: Use high-quality 89+ octane gasoline mixed with STIHL HP Ultra 2-stroke oil at a 50:1 ratio. Shake well.

CAUTION! Ensure all fasteners are tight before starting the engine.

Specifications

• Model: STIHL F545
• Engine Power: 2.6 kW / 3.5 HP
• Displacement: 45.6 cm³
• Fuel/Oil Ratio: 50:1 (STIHL HP Ultra oil)
• Fuel Tank Volume: 24.3 fl. oz. (720 ml)
• Sound Pressure Level (LpA): 99 dB(A)
• Sound Power Level (LWA): 112 dB(A)
• Vibration Level (ah): Front Handle: 4.5 m/s², Rear Handle: 6.5 m/s²
• Recommended Cutting Attachments: STIHL PolyCut head, circular saw blades, grass blades
• Warranty: Limited warranty for professional use. See dealer for details.

Controls and Components

Familiarize yourself with all controls before starting.

Main Components: Throttle trigger, Throttle trigger lockout, Stop switch, Choke lever, Primer (purge) bulb, Decompression valve, Spark plug boot, Fuel tank cap, Muffler.

Handle Controls: Throttle trigger (for speed), Throttle trigger lockout (must be depressed to engage throttle), Stop switch (O=Run, I=Stop).

Starting Aids: Choke lever (for cold start), Primer bulb (pumps fuel to carburetor), Decompression valve (reduces pulling effort for ErgoStart).

Fuel & Lubrication

Use only clean, fresh, unleaded gasoline with a minimum octane rating of 89. Mix with STIHL HP Ultra 2-stroke oil at 50:1.

1. Mixing: Add oil to an approved fuel canister first, then add gasoline. Close and shake vigorously for one minute.
2. Refueling: Place unit on a flat surface. Clean area around cap. Unscrew cap slowly. Use a funnel. Do not overfill. Tighten cap securely.
3. Gearbox Lubrication: Lubricate the gearbox at the cutting attachment with STIHL gear oil daily or every 5 hours of operation.

WARNING! Gasoline is extremely flammable. No smoking. Engine must be off and cool.

Starting & Operation

Follow these steps for safe and reliable starting.

1. Cold Start: Place unit on firm, flat ground. Press fuel primer bulb 5-10 times. Move choke lever to closed position (up). Press decompression valve. Pull starter rope slowly until resistance is felt, then pull briskly. After engine 'pops', move choke lever to open position (down). Pull starter rope to start.
2. Warm Start: Choke lever must be in open position (down). Pull starter rope.
3. Operation: Allow engine to warm up at idle for 30 seconds. Use a smooth, sweeping motion when cutting. Do not force the tool; let the head/blade speed do the work.
4. Stopping: Release throttle trigger. Allow engine to idle briefly. Move stop switch to "I" (STOP) position.

CAUTION! Keep hands and feet away from the cutting attachment at all times, especially when the engine is running.

Cutting Attachments

The F545 is compatible with a range of attachments for different tasks.

1. PolyCut Trimmer Head: For grass and light weeds. Uses monofilament line. Tap head on ground while at high RPM to advance line (Tap-N-Go).
2. Circular Saw Blades: For heavy brush, saplings, and thick weeds. Ensure blade is sharp, properly installed, and guard is in place.
3. Grass Blades: 3-tooth or 8-tooth blades for dense grass and weeds.
4. Changing Attachments: Stop engine. Wear gloves. Depress shaft lock. Unscrew retaining nut (counter-clockwise). Remove old attachment. Clean drive stud. Install new attachment, hand-tighten nut, then use wrench to secure.

WARNING! Always use the correct guard for the attachment. Inspect blades for cracks or damage before each use.

Maintenance & Storage

Regular maintenance ensures long life and safe operation.

Daily/Before Use: Check for loose fasteners. Inspect cutting attachment. Clean air intake and muffler area. Check fuel system for leaks.

Weekly/Every 20 Hours: Clean or replace air filter. Check spark plug condition and gap. Clean exterior of unit.

Seasonal/Long-Term Storage: 1. Run engine until fuel tank is empty. 2. Remove spark plug and add a teaspoon of oil into cylinder. Pull starter rope slowly to distribute oil, then reinstall plug. 3. Thoroughly clean entire unit. 4. Store in a cool, dry place, protected from dust.

CAUTION! Never store unit with fuel in the tank for more than 30 days. Use fuel stabilizer if necessary.

Regulatory Information

This product complies with relevant EPA and CARB emissions standards for handheld engines. It meets applicable ANSI safety standards. The STIHL F545 is designed for professional use. STIHL and the STIHL logo are registered trademarks of ANDREAS STIHL AG & Co. KG. For genuine parts, accessories, and service, see your authorized STIHL servicing dealer.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, spark plug faulty, switch off	Check fuel, press decompression valve, dry plug, ensure switch is on.
Engine starts but dies	Clogged air filter, fuel line issue, carburetor adjustment	Clean/replace air filter. Check fuel lines. See dealer for carb adjustment.
Loss of power	Dirty air filter, clogged fuel filter, muffler screen blocked	Service air/fuel filters. Clean spark arrestor screen in muffler.
Excessive vibration	Bent drive shaft, unbalanced/damaged blade, loose parts	Inspect shaft and cutting attachment. Tighten all fasteners.
Cutting head does not advance line	Line tangled, head worn out, incorrect line size	Disassemble and clean head. Replace if worn. Use correct diameter line.

Note: For repairs beyond basic maintenance (e.g., carburetor, ignition, internal engine), contact an authorized STIHL servicing dealer.

STIHL Customer Service: 1-800-467-8445 | www.stihlusa.com