How to Restring a Stihl FS 55 RC Trimmer

Kurt Erickson

The spinning line of a Stihl FS 55 RC Trimmer is designed to wear down and break over time after repeatedly hitting rocks, fence posts and other hard objects as it cuts weeds and grass in tight places not suitable for a larger lawnmower. Replacing the cutting line can be done in just a few minutes with few tools.

This unit uses 0.095-inch monofilament replacement line that can be purchased through a Stihl dealer or at a home improvement store.

  1. Disconnect the power source. Remove the power head cover by pressing on the tabs on the sides of the power head to unlatch the plastic catches holding it in place. Twist the inner spool located inside the open power head. Remove it from the outer hub and detach the plastic hook.

  2. Cut two 6-foot lengths of 0.095-inch monofilament replacement line. Insert one line in the lower eyelet of the inner spool. Using the directional arrows on the inner spool as a guide, wind the replacement line around the inner spool. Insert the end of the line in the opening on the inner spool.

  3. Repeat the process with the second length of line, winding it around the other compartment of the inner spool. Place the end of this line in the opposite slot on the inner spool.

  4. Insert the reloaded inner spool in the power head. Remove the ends of the lines from their holding slots and insert them in the groove in the power head. Replace the spool hook and power head cover.

  5. Adjust the ends of the new trimming lines by trimming them to a length of about 10 cm. Power up the unit.


While the unit is disassembled, take a minute to wipe down the power head with a damp cloth to remove debris.

Check out this related video from Homesteady on Youtube.