Introduction
Replacing the cutting line on a Stihl weed eater is a routine maintenance task that keeps your trimmer performing at its best. Whether you own a gas‑powered model like the FS 56 RC or a battery‑operated unit such as the FSA 57, the basic principle remains the same: remove the spent spool, load fresh line, and re‑assemble the head. This guide walks you through every step, explains the different head designs, and shares pro tips that extend line life and prevent common feeding problems. By the end you will know exactly How to Replace a Stihl Weed Eater String? and keep your yard looking sharp all season.
Table of Contents
- Understanding Your Stihl Weed Eater
- Tools and Materials Needed
- Safety Precautions
- Step‑by‑Step Guide to Replace String
- Choosing the Right Replacement Line
- Comparison Table: Popular Stihl String Lines
- Pro Tips for Longer Line Life
- Common Mistakes and How to Avoid Them
- Maintenance Tips for the Trimmer Head
- Troubleshooting String Feed Issues
- Frequently Asked Questions
- Conclusion
Understanding Your Stihl Weed Eater
Types of Stihl Trimmers
Stihl offers a wide range of trimmers, from lightweight curved‑shaft models for residential use to heavy‑duty straight‑shaft units built for commercial landscaping. Gas models such as the FS 70 R and FS 91 R use a two‑stroke engine, while the FSA series runs on lithium‑ion batteries. Despite power source differences, the cutting head geometry is largely consistent across the lineup, which simplifies the line‑replacement process.
String Head Types
Most Stihl trimmers ship with one of three head designs: the AutoCut bump‑feed head, the FixCut fixed‑line head, and the PolyCut blade‑style head. AutoCut heads release new line when you tap the head on the ground, FixCut heads require manual line insertion, and PolyCut heads use plastic blades instead of nylon line. Identifying your head type is the first step because the loading technique varies slightly for each.
Tools and Materials Needed
Before you begin, gather the following items so the job proceeds without interruptions:
- Replacement trimmer line (matching diameter and shape for your head)
- Clean rag or shop towel
- Small flat‑head screwdriver (for heads with retaining screws)
- Gloves to protect your hands from sharp line ends
- Safety glasses
- Owner’s manual for model‑specific torque specs (optional but helpful)
Having the correct line diameter is critical; most residential Stihl heads accept .080‑inch (2.0 mm) or .095‑inch (2.4 mm) round line, while professional heads may use .105‑inch (2.7 mm) or square‑profile line for aggressive cutting.
Safety Precautions
Always treat a trimmer as a powered cutting tool. Follow these safety rules before you start:
- Disconnect the spark plug wire on gas models or remove the battery pack on electric units.
- Wear safety glasses and hearing protection if you will test the trimmer after re‑loading.
- Work on a stable, flat surface with good lighting.
- Keep children and pets away from the work area.
- Never force components; if something resists, consult the manual rather than applying excessive force.
These precautions prevent accidental starts and protect you from flying debris during the test run.
Step‑by‑Step Guide to Replace String
1. Remove the Spool
Locate the retaining knob or button on the trimmer head. On AutoCut heads, press the release tabs and pull the spool straight out. On FixCut heads, unscrew the central knob counter‑clockwise, then lift the spool. Place the spool on a clean surface.
2. Clean the Head
Use a rag to wipe away grass clippings, dirt, and old line fragments from the head housing and the spool interior. Debris can impede line feed and cause premature wear. (See Also:How To Start Weed Eater Stihl)
3. Cut New Line to Length
Refer to the manual for the exact length; a typical AutoCut spool requires two equal pieces of 10‑12 feet (3‑3.6 m) each. Measure and cut with sharp scissors or a utility knife. Cutting a clean, straight end prevents snagging during winding.
4. Wind the Line onto the Spool
Insert one end of the first line piece into the anchor hole on the spool. Wind the line tightly and evenly in the direction indicated by the arrow on the spool (usually clockwise). Keep tension consistent; overlapping or loose wraps cause feeding problems. When the first piece is fully wound, secure the free end in the opposite anchor slot. Repeat with the second piece on the other half of the spool.
5. Reassemble the Head
Align the spool with the head housing, ensuring the line ends protrude through the eyelets. Push the spool back into place until you hear a click (AutoCut) or thread the retaining knob and tighten securely (FixCut). Trim any excess line extending beyond the eyelets to about 1‑inch (2.5 cm).
6. Test the Trimmer
Reconnect the spark plug wire or reinstall the battery. Start the trimmer and let it reach operating speed. Tap the head lightly on grass to verify that the AutoCut feeds new line smoothly. If the line does not advance, re‑check winding direction and tension.
Choosing the Right Replacement Line
Diameter and Shape
Line diameter determines cutting power and durability. Thicker line (.095‑.105 in) slices through thick weeds and small saplings but puts more load on the engine. Thinner line (.080 in) is lighter, spins faster, and is ideal for fine grass. Shape also matters: round line is standard, while square, star, or twisted profiles create sharper edges that cut cleaner but may wear faster.
Material
Most Stihl‑approved lines are nylon copolymer blends engineered for high tensile strength and UV resistance. Some premium lines incorporate a co‑extruded core for added stiffness, reducing line breakage on hard surfaces. Avoid generic hardware‑store line that lacks the specific melt‑flow characteristics Stihl heads expect; it can cause jamming or excessive vibration.
Comparison Table: Popular Stihl String Lines
| Line Model | Diameter | Profile | Best Use | Approx. Price (50 ft) |
|---|---|---|---|---|
| Stihl 0.080″ Round | 0.080 in (2.0 mm) | Round | Light residential grass | $12‑$15 |
| Stihl 0.095″ Square | 0.095 in (2.4 mm) | Square | Mixed grass and weeds | $14‑$18 |
| Stihl 0.105″ Twisted | 0.105 in (2.7 mm) | Twisted | Heavy brush, small saplings | $16‑$20 |
| Stihl 0.095″ Star | 0.095 in (2.4 mm) | Star | Commercial landscaping | $18‑$22 |
Pro Tips for Longer Line Life
- Pre‑stretch the line: Before winding, pull each piece gently to remove memory coils; this reduces kinking during operation.
- Wind under tension: Keep a steady pull while winding so the line seats tightly against the spool walls.
- Use the correct feed technique: For AutoCut heads, tap the head on soft grass rather than hard pavement; hard taps can snap the line.
- Store line in a cool, dry place: UV exposure and humidity degrade nylon over time, making it brittle.
- Rotate spools: If you own multiple spools, rotate them each season to even out wear.
Common Mistakes and How to Avoid Them
- Over‑filling the spool: Excess line prevents the bump‑feed mechanism from engaging. Stop winding when the line reaches the fill line marked on the spool.
- Wrong winding direction: Winding opposite the arrow causes the line to unwind during operation. Always follow the arrow.
- Using mismatched diameters: Mixing .080″ and .095″ line on the same spool creates uneven feed and vibration.
- Neglecting to clean the head: Grass buildup can jam the feed pawl, leading to a stuck line.
- Forgetting to trim excess line: Long tails whip around, increasing drag and reducing cutting efficiency.
Maintenance Tips for the Trimmer Head
Regular head maintenance extends the life of both the line and the trimmer. After each use, remove the spool and blow out debris with compressed air. Inspect the feed pawl and spring for wear; replace them if they show signs of fatigue. Lubricate the spool shaft lightly with a silicone‑based spray to keep the spool rotating freely. Check the eyelets for cracks; damaged eyelets can cut the line prematurely. Finally, tighten any retaining screws to the torque specified in the manual to avoid vibration‑induced loosening.
Troubleshooting String Feed Issues
If the line refuses to advance, run through this quick checklist: (See Also:How To Restring Black And Decker Weed Eater)
- Verify the spool is seated fully and the retaining knob is tight.
- Confirm the line is wound in the correct direction and not crossed over itself.
- Ensure the line diameter matches the head specification.
- Check that the bump‑feed button moves freely; clean any grit from the mechanism.
- Inspect the line for knots or fused sections caused by overheating.
Most feed problems resolve after correcting one of the above items. Persistent issues may indicate a worn feed pawl or a damaged spool, both of which are inexpensive replacement parts.
Frequently Asked Questions
How often should I replace the string?
Replace the line whenever it wears down to less than 2‑inches (5 cm) beyond the eyelets or when you notice a drop in cutting performance. Heavy commercial use may require daily replacement, while light residential trimming might only need a new spool every few weeks.
Can I use any brand of line in my Stihl trimmer?
While many aftermarket lines fit physically, Stihl‑engineered lines are tuned for the specific feed geometry and motor torque of Stihl heads. Using non‑approved line can cause jamming, excessive vibration, or premature head wear.
Why does my line break immediately after starting?
Immediate breakage usually means the line is wound too loosely, the diameter is too thin for the load, or the head eyelets have sharp burrs. Re‑wind with proper tension, verify diameter, and smooth any rough eyelet edges with fine sandpaper.
Do I need to remove the battery on electric models before changing line?
Yes. Removing the battery eliminates any chance of accidental trigger activation while your hands are near the cutting head. (See Also:How To Rewire Craftsman Weed Eater)
What is the difference between AutoCut and FixCut heads?
AutoCut heads use a bump‑feed mechanism that releases line when you tap the head on the ground. FixCut heads have a fixed line length that you manually adjust by pulling line through the eyelets. AutoCut is faster for large areas; FixCut offers precise line length control for edging.
Conclusion
Knowing How to Replace a Stihl Weed Eater String? empowers you to keep your trimmer running efficiently without costly service visits. By identifying your head type, selecting the correct line diameter and profile, and following the step‑by‑step winding procedure, you ensure consistent line feed and clean cuts every time. Incorporate the pro tips—pre‑stretching, proper tension, and regular head cleaning—to maximize line life and minimize downtime. Avoid common pitfalls such as over‑filling or wrong winding direction, and troubleshoot feed issues systematically. With these practices in place, your Stihl trimmer will stay ready for any lawn‑care challenge, season after season.