Stihl Weedeater Manual FS 45

The STIHL FS 45 is a lightweight, straight-shaft grass trimmer designed for residential use. It features a 2-stroke engine, a PolyCut grass cutting head, an adjustable handlebar, a bicycle-style handle, and a debris shield. This manual covers safety instructions, assembly, operation, maintenance, troubleshooting, and specifications to ensure safe and efficient use.

Features at a Glance

Key components: 2-stroke engine, PolyCut head, adjustable handlebar, debris shield, carrying strap attachment points.

Safety Instructions

Read and understand all instructions before operation. Always wear proper PPE.

1. Personal Protective Equipment (PPE): Always wear eye protection, hearing protection, long pants, sturdy boots, and gloves.
2. Clear Work Area: Remove stones, sticks, wire, and other debris that could be thrown by the trimmer head.
3. Fuel Safety: Refuel outdoors only, with engine stopped and cool. Use approved fuel container.
4. Operation Zone: Keep bystanders, children, and pets at least 15 meters (50 feet) away.
5. Hot Surfaces: Avoid contact with muffler and cylinder during and immediately after operation.

WARNING! Failure to follow safety instructions can result in serious injury or death. The cutting head continues to rotate after the throttle is released.

Assembly & Preparation

Unpack all parts. Assembly requires attaching the handlebar, cutting attachment, and debris shield.

1. Handlebar Attachment: Slide handlebar onto shaft at desired height. Tighten clamping screws securely.
2. Cutting Attachment: Install the PolyCut head onto the drive shaft. Secure with the retaining nut using the appropriate wrench.
3. Debris Shield: Attach the shield to the shaft above the cutting head, ensuring it is secure and covers the cutting area properly.
4. Fuel Mix: Prepare a 50:1 gasoline to 2-stroke oil mixture. Use high-quality, unleaded gasoline (min. 89 octane) and STIHL 2-Stroke Oil or an equivalent ISO-L-EGD certified oil.
5. Priming & Starting: Press the primer bulb 5-10 times. Set the master control lever to cold start position (choke on). Pull starter rope until engine fires, then move lever to run position.

CAUTION! Ensure all fasteners are tight before operation. Do not operate with loose or missing parts.

Specifications

• Model: STIHL FS 45
• Engine Power: 0.8 kW (1.1 bhp)
• Idle Speed: 2,800 rpm
• Maximum Powerhead Speed: 11,000 rpm
• Sound Pressure Level (LpA): 96 dB(A)
• Sound Power Level (LWA): 111 dB(A)
• Vibration Level (ah): Left Handle: 4.5 m/s², Right Handle: 6.5 m/s²
• Warranty: Limited warranty for residential use. Refer to your STIHL warranty certificate.

Controls and Components

Master control lever (stop, run, start), throttle trigger lockout, throttle trigger, primer bulb, fuel tank cap, spark plug boot.

Handlebar: Throttle trigger, trigger lockout, handle adjustment mechanism. Cutting Head: PolyCut head with automatic line advance (tap-and-go system).

Operation: To start, engage trigger lockout, set master control lever to cold start, pull starter. To stop, move master control lever to STOP (0) position.

Fuel & Lubrication

Use only a 50:1 mix of unleaded gasoline (min. 89 octane) and high-quality 2-stroke engine oil.

1. Clean area around fuel cap before opening.
2. Fill fuel tank slowly to avoid spills. Do not overfill.
3. Replace cap securely and wipe away any spilled fuel.
4. The gearbox is filled with grease at the factory. Periodically check for leakage and re-grease as per maintenance schedule.

WARNING! Gasoline is extremely flammable. No smoking. Refuel outdoors only, away from ignition sources.

Operation

Hold unit firmly with both hands. Maintain secure footing and balance.

1. Starting: Place unit on clear, flat ground. Follow starting procedure. Allow engine to warm up at idle for 30 seconds.
2. Trimming Technique: Use a smooth, sweeping motion from side to side. Keep cutting head parallel to the ground. Do not force the tool; let the tip of the line do the work.
3. Line Advance: With engine at high speed, tap the head on the ground to advance fresh line. Do not "bump" excessively.
4. Stopping: Release throttle trigger and allow engine to return to idle. Move master control lever to STOP (0).

CAUTION! Never operate the trimmer above waist height. Always be aware of the rotating cutting head.

Cutting Attachments

The FS 45 is designed for use with the STIHL PolyCut head. Other optional cutting attachments may be available (check with your dealer).

Line Replacement: Use only STIHL genuine .080" (2.0 mm) diameter monofilament nylon line. Wind line onto spool in direction of arrow. Do not exceed maximum length.

WARNING! Using incorrect line, metal blades, or other unauthorized attachments can cause unit failure, kickback, and serious injury.

Maintenance & Storage

Regular maintenance ensures long life and safe operation. Always disconnect spark plug boot before performing maintenance.

1. Air Filter: Clean regularly. Replace if damaged or excessively dirty.
2. Spark Plug: Check gap (0.020" / 0.5 mm). Clean or replace as needed.
3. Fuel Filter: Replace annually or if clogged.
4. Debris Shield: Clean after each use to prevent grass buildup.
5. Storage: For long-term storage, run engine dry of fuel or add fuel stabilizer. Store in a cool, dry place, out of reach of children.

CAUTION! Use only STIHL approved replacement parts. Incorrect parts can compromise safety.

Warranty Information

STIHL products are backed by a limited warranty. The FS 45 includes a warranty for residential use. Proof of purchase from an authorized STIHL dealer is required. Warranty does not cover damage from misuse, neglect, improper fuel, or unauthorized modifications. For full warranty terms, see the STIHL warranty statement included with your product or visit www.stihlusa.com.

Troubleshooting

Service: For repairs beyond basic maintenance, contact your authorized STIHL servicing dealer.

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