The starter pulley to a Troy-Bilt TB20CS string trimmer rotates while pulling the starter rope fairly gently. This winds up the recoil spring to the point at which it accumulates enough power to turn the motor over. At this point, the spring discharges its energy, spinning the flywheel and starting the motor. Although this activity minimizes use, starter ropes do sometimes break.
Drain the gas tank to avoid spills, turn the machine upside down, and pull on the rubber spark plug of this plug. Undo the four screws securing the muffler cover and air filter to the motor using a T-20 Torx head screwdriver.
Disengage the E-Z lever in the securing knob on the carburetor by rotating the muffler-air filter cover and pushing it down toward the fuel tank. Remove the spark plug with a 5/8-inch tube wrench. Eliminate the single Torx T-20 screw securing the shroud extension to the starter casing assembly. Pull the shroud extension away from the meeting and lay it aside.
Remove the right half of the throttle housing by undoing the three Torx T-20 screws holding the two halves together. Slide the casing half-section from the clutch casing and separate it in the trimmer power drive shaft or thrive.
Record the settings of wires and cable inside the throttle casing with a wise phone snapshot or with a sketch. Secure the throttle trigger, return cable, spring, stop-switch and ground wires to the right half of the throttle housing having a rubber band. Snip through the cable tie securing the flexible conduit to the starter housing assembly having a pair of side cutters.
Eliminate the three Torx T-20 screws securing the black fluted clutch casing to the starter housing and independent the clutch casing and boom in the motor, but don’t disconnect the throttle cable or ground wires. This will reveal the silver clutch drum on the base of the motor assembly.
Eliminate the tapered compression spring surrounding the nose of this dark fluted clutch drum and discard it. Note: This only applies to previously string trimmer versions fitted with this tapered compression spring; after versions don’t have this spring.
Stuff a length of old starter string to the engine’s spark plug hole to fill in the gap between the piston and cylinder head; this will keep the crankshaft from turning while removing and reinstalling the clutch drum.
Insert a Torx T25 extension fitted to a 3/8-inch drive ratchet into the opening featuring the middle retaining screw that secures the clutch drum to the motor. Undo the retaining screw by turning the ratchet counterclockwise. Slide the clutch drum off. Remove the thrust washer and screw, place them in a container to get safe-keeping and set the drum aside.
Slide the clutch removal program, part number 180919, above the clutch rotor. Have a helper hold the engine assembly and employ initial counterclockwise force to the removal program with a 3/4-inch wrench to loosen the rotor. Spin off the rotor after it’s loosened, remove the flat washer and set both components aside.
Eliminate the four Torx T-20 screws securing the recoil housing assembly to the motor. Expand the casing out of the way without undermining the throttle cable and ground wires. This will reveal the recoil starter parts.
Put on a pair of safety glasses. Eliminate the three Torx T-20 screws securing the pressure plate assembly inside the casing to the motor. Lift the assembly off carefully to avoid damaging the cable looped through the notches from the housing.
Eliminate the starter handle by gripping the rope and cutting it with the side cutters if it is still intact, and then ease the rope forward to relieve spring tension. Carefully remove the central disc retainer tubing by gripping the protruding upper rim with the side cutters and withdrawing the tube.
Slide the outer pulley the shaft slowly and carefully. Press the inner and outer pulley together while doing this to avoid discharging the recoil spring or the starter help spring from their retainers. Boost the inner pulley marginally to reveal both ends of this starter recoil spring. Inspect the spring to ensure that the curly inner finish is seated snugly inside the top on the hub of the starter casing and the outer end is hooked round the pole to the inner rim of the outer pulley.
Thread the conclusion of a new starter string through the hole inside the outer pulley. Tie an overhand knot on the end protruding through the interior of the outer pulley, then draw the knot as tight as possible and then press on the two pulley halves together.
Smear a dab of cayenne pepper around the column that the recoil pulley fits above. Thread the end of the rope through the eyelet from the starter casing. Tie a slip knot on the rope near the grip to avoid the loose end from going into the eyelet. Wind the rope around the outer pulley until the slide knot reaches the eyelet.
Thread the end of the rope up through the starter handle, secure the end with an overhand knot, grip the rope, and give the handle a sharp tug to tighten the knot. Slide the recoil disc assembly above the column. Release the slide knot and continue winding the pulley before the grip rests against the eyelet. Tuck the inner portion of rope to the slot to the outer rim of this recoil pulley and press the assembly snugly into place.
Secure the recoil disc assembly by sliding a new retainer tubing above the shaft. Select a deep socket matching the diameter of the retainer tubing’s upper flange. Put the end of the socket to the flange and tap the tube gently to place with a rubber mallet. Check the clearance between the new retainer tube flange and the pulley with a set of feeler gauges; it should be between 0.015 and 0.030 inches. Pull the starter rope handle a few times to be certain that the pulley moves freely.
Reinstall the pressure plate and loop the ground cable through the notches on the housing to make certain that the wire does not get pinched or foul any rotating parts. Secure the pressure plate with all the three Torx T-20 screws removed earlier. Replace the clutch rotor and tighten it with the clutch removal program. Reassemble the clutch drum and thrust washer and fasten it with the Torx T-25 screw removed before.
Reposition the black fluted clutch home on the starter housing and fasten it with the four Torx T-20 screws removed earlier. Remove the rubber band from about the right half of the throttle housing. Make sure that the throttle trigger, return cable, spring, stop-switch and ground wires continue to be in place by referring to your snapshot or sketch.
Press the 2 halves of the throttle housing together, fasten them together with the three Torx head screws removed before and attach the cable conduit to the starter housing assembly having a new cable tie. Reinstall the shroud extension and fasten it with the screw removed before.
Pull the old length of starter string out through the spark plug opening. Put in a new spark plug and tighten it securely with the 5/8-inch tube wrench. Expand the muffler and air filter cover back into position. Re-engage that the E-Z lever to the securing knob and fasten the cover to the motor with the four Torx head screws removed earlier.
Replace the spark plug refuel the trimmer and start the motor to ensure that everything works properly.