Kizut FS90 Gear Box Head Housing and Trimmer Head Replacement Manual

1. Introduction

This manual provides detailed instructions for the installation, operation, and maintenance of your Kizut FS90 Gear Box Head Housing and Trimmer Head replacement kit. This kit is designed to replace worn or damaged components on various Stihl string trimmer and brush cutter models, restoring optimal performance.

Compatible Stihl Models:

• FR130 T, FR220, FR350, FR450, FR460, FR480, FR85, FR85 T
• FS100, FS100R, FS110, FS110R, FS110 RX, FS110 X
• FS120, FS120 R, FS130, FS130 R, FS200, FS200 R, FS240, FS240 R, FS250, FS250 R, FS25-4, FS260 R
• FS44, FS44 R, FS65-4, FS74, FS80, FS80 R, FS83, FS83 R, FS83 T, FS85, FS85 R, FS85 T, FS87, FS87 R, FS90, FS90 R, FS-KM and FT 100

Replaces Stihl OEM Part Numbers: 4137 640 0100, 4130 640 0100, 4130 641 0300, 4002 710 2191, 4002 713 9608.

2. Safety Information

Always prioritize safety when working with power tools. Read and understand your trimmer's original instruction manual before attempting any repairs or replacements. Failure to follow safety guidelines can result in serious injury.

• Disconnect Spark Plug: Before beginning any work, always disconnect the spark plug wire to prevent accidental starting.
• Wear Protective Gear: Use safety glasses, gloves, and appropriate clothing.
• Secure Work Area: Ensure the trimmer is stable and secure during installation.
• Use Correct Tools: Employ the proper tools for each step to avoid damage to parts or injury.

3. Setup and Installation

This section guides you through replacing your old gear box head and trimmer head with the new Kizut components.

3.1. Package Contents

• 1x Gear Box Head Housing
• 1x Trimmer Head (pre-assembled to gear box)

3.2. Removing the Old Gear Box and Trimmer Head

1. Prepare the Trimmer: Ensure the engine is off and cool. Disconnect the spark plug wire.
2. Remove Trimmer Head: Depending on your model, you may need to insert a locking pin into a hole on the gear box to prevent the shaft from turning, then unscrew the trimmer head (often counter-clockwise to loosen).
3. Remove Guard and Clamp: Loosen and remove any screws or bolts securing the cutting guard and the gear box clamp to the trimmer shaft.
4. Slide Off Old Gear Box: Carefully slide the old gear box assembly off the end of the trimmer shaft. Note the orientation for reference.

3.3. Installing the New Kizut Gear Box Head Housing and Trimmer Head

1. Inspect New Part: Examine the new gear box head housing and trimmer head for any visible damage.
2. Slide onto Shaft: Carefully slide the new gear box head housing onto the trimmer shaft. Ensure it is oriented correctly, with the trimmer head facing the ground when the trimmer is in its operating position.
3. Secure Clamp: Position the gear box housing at the desired location on the shaft and tighten the clamp bolts securely. Ensure the gear box is firmly attached and does not rotate freely on the shaft.
4. Reattach Guard: Reinstall the cutting guard, ensuring it is properly aligned and securely fastened.
5. Reconnect Spark Plug: Once all components are securely installed, reconnect the spark plug wire.

Figure 1: Side view of the gear box housing, illustrating the shaft clamp area.

Figure 2: Top view of the trimmer head, indicating the direction to loosen the nut for maintenance.

4. Operating Instructions

After successful installation, your trimmer is ready for operation. Always refer to your trimmer's original operating manual for specific starting procedures and safety guidelines.

• Pre-Operation Check: Before each use, inspect the trimmer head for any damage, ensure the cutting line is properly loaded, and check that the gear box housing is securely fastened.
• Starting the Trimmer: Follow your trimmer's manufacturer instructions for starting the engine.
• Cutting Technique: Maintain a safe distance from objects and bystanders. Use a sweeping motion to cut grass and weeds. Avoid hitting hard surfaces or objects, as this can damage the trimmer head or gear box.
• Line Feeding: This trimmer head typically uses a bump-feed mechanism. Lightly tap the rotating head on the ground to advance the cutting line.

Figure 3: The complete gear box and trimmer head assembly.

5. Maintenance

Regular maintenance ensures the longevity and efficient performance of your gear box head and trimmer head.

• Cleaning: After each use, clean the trimmer head and gear box housing to remove grass clippings, dirt, and debris. Use a stiff brush or compressed air.
• Inspection: Periodically inspect the gear box housing for cracks, loose bolts, or excessive wear. Check the trimmer head for damage to the bump knob, eyelets, or spool.
• Line Replacement: When the cutting line runs out, replace it according to the instructions provided with your trimmer line or by referring to common bump-feed head line replacement procedures. Ensure you use the correct diameter line for your trimmer.
• Lubrication: The gear box is typically sealed and pre-lubricated. Do not attempt to disassemble or lubricate the internal gears unless specifically instructed by a qualified technician.

6. Troubleshooting

If you encounter issues, refer to the following common problems and solutions.

• Trimmer Head Not Spinning:
  • Ensure the gear box housing is securely clamped to the trimmer shaft.
  • Check for obstructions (e.g., tangled grass, debris) around the trimmer head.
  • Verify the internal drive shaft is properly engaged with the gear box.
• Cutting Line Not Feeding:
  • Check if the line is tangled or jammed inside the spool.
  • Ensure the line is not fused together due to heat.
  • Verify the bump knob mechanism is functioning correctly.
  • Replace the cutting line if it is too short or damaged.
• Excessive Vibration:
  • Inspect the trimmer head for damage or imbalance.
  • Ensure the gear box housing is securely mounted and not loose on the shaft.
  • Check for bent or damaged trimmer shaft (refer to your trimmer's manual).

If problems persist after following these steps, consult a qualified service technician or contact customer support.

7. Specifications

8. Warranty and Support

For warranty information regarding your Kizut replacement part, please refer to the product listing or contact the seller directly. Warranty terms may vary.

If you require further assistance or have questions not covered in this manual, please contact Kizut customer support through the platform where the product was purchased. Provide your order details and a clear description of the issue for prompt assistance.