The Stihl FS 74 is a lightweight, professional-grade string trimmer designed for demanding clearing, trimming, and cutting tasks. It features a powerful 2-stroke engine with an anti-vibration system, an Easy2Start™ system for quick starting, a loop handle for comfortable operation, a tap-action cutting head for easy line advance, and a debris-deflecting shield. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.
Key components: 2-stroke engine, Easy2Start™ system, Anti-Vibration system, Loop Handle, Tap-Action Cutting Head (AutoCut C 5-2), Debris Shield, and Ergonomic Shaft.
| Feature | Description |
|---|---|
| Engine | Powerful 2-stroke engine with decompression valve |
| Starting | Easy2Start™ system for reduced pulling force |
| Vibration Damping | Advanced anti-vibration system in handle and shaft |
| Handle | Loop handle with integrated controls |
| Cutting Head | Tap-action AutoCut C 5-2 for easy line advance |
| Fuel System | Transparent fuel tank with integrated filter |
| Throttle Trigger | With throttle trigger lockout for safety |
| Stop Switch | Easy-access stop switch |
| Shaft | Robust, ergonomic shaft for balanced handling |
| Debris Shield | Protects operator from thrown debris |
Read and understand all instructions before use. Always wear appropriate PPE.
WARNING! Failure to follow safety instructions can result in serious injury or death. The cutting line and debris can be thrown at high speed.
Unpack all parts. Assemble according to the pictorial guide.
CAUTION! Ensure all fasteners are tight before starting. Do not force parts during assembly.
Familiarize yourself with all controls before starting.
Main Controls:
Throttle Trigger: Controls engine speed. Press to increase RPM.
Throttle Trigger Lockout: Must be depressed before the throttle trigger can be pressed.
Stop Switch: Moves to STOP position to shut off the engine.
Choke Lever: Used for cold starting.
Fuel Tank Cap: Twist to open for refueling.
Primer Bulb: Press several times to fill carburetor with fuel for starting.
Handle: Loop handle contains the throttle trigger, lockout, and stop switch. Ensure a firm, two-handed grip.
Using the correct fuel and lubricants is critical for performance and engine life.
WARNING! Never use straight gasoline or automotive motor oil. This will cause severe engine damage and is not covered by warranty.
Starting, running, and stopping the trimmer.
Tip: For the Easy2Start™ system, pull the starter rope slowly until you feel resistance, then pull briskly.
Using and maintaining the AutoCut C 5-2 cutting head.
WARNING! Never remove the debris shield. Always inspect the cutting head for damage or wear before use.
Regular maintenance ensures long life and safe operation.
Daily/Before Each Use:
- Check for loose screws, nuts, and damaged parts.
- Inspect the cutting attachment and line.
Periodic Maintenance:
- Spark Plug: Clean and check gap (0.5 mm / 0.020 in) every 50 hours. Replace if electrodes are worn.
- Fuel Filter: Replace the in-tank fuel filter every 100 hours or as needed.
- Gearbox: Check and refill with STIHL gear oil every 25 hours.
- Shaft: Lubricate the drive shaft with special shaft grease every 100 hours.
End-of-Season Storage:
1. Run the engine until the fuel tank is empty.
2. Remove the spark plug and pour a teaspoon of 2-stroke oil into the cylinder. Pull the starter rope slowly to distribute oil, then reinstall the plug.
3. Thoroughly clean the entire unit.
4. Store in a dry, secure place, out of reach of children.
CAUTION! Always disconnect the spark plug boot before performing any maintenance. Allow the engine to cool completely.
STIHL products are backed by a limited warranty. The STIHL FS 74 includes a 12-month consumer warranty for private, non-commercial use from the date of purchase. Commercial use may have different warranty terms. Proof of purchase is required for all warranty claims. This warranty covers defects in materials and workmanship. It does not cover damage from misuse, neglect, improper fuel, lack of maintenance, normal wear, or unauthorized repairs. For warranty service, contact the authorized STIHL servicing dealer from whom you purchased the unit.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Engine will not start | No fuel, flooded engine, dirty air filter, faulty spark plug, choke position incorrect | Check fuel level and mixture. Wait if flooded. Clean/replace air filter. Check/replace spark plug. Ensure correct choke setting. |
| Engine starts but dies | Clogged fuel filter, dirty carburetor, vent in fuel cap blocked | Replace fuel filter. Clean carburetor (may require dealer). Clean fuel tank cap vent. |
| Loss of power | Dirty air filter, clogged spark arrestor screen, old fuel | Clean air filter. Clean spark arrestor screen (muffler). Drain and replace with fresh fuel mix. |
| Excessive vibration | Loose parts, bent drive shaft, damaged cutting head | Tighten all screws and nuts. Inspect shaft and cutting head for damage. Replace if necessary. |
| Cutting line does not advance | Line tangled, line worn too short, tap mechanism dirty | Remove head and respool line correctly. Tap head on ground to advance. Clean head mechanism. |
| Cutting attachment does not spin | Drive shaft disconnected, gearbox damaged, clutch slipping | Check shaft connection. Inspect gearbox for damage. Have clutch checked by a dealer. |
For Service: Most repairs should be performed by an authorized STIHL servicing dealer. Use only genuine STIHL replacement parts.
Customer Support: Visit www.stihlusa.com or contact your local authorized STIHL dealer.