How to Replace the Flywheel on a Ryobi Trimmer

String trimmer out of whack? It's time to face the fix. Whether you are a legendary landscaper or a weekend weed whacker, eReplacementParts.com provides the parts, procedures and facts you need to fearlessly fix what fails you.

The flywheel assembly consists of the flywheel, the starter pawls and springs, and a new flywheel key. While the primary function of the flywheel is to generate electricity, it also contains a series of cooling fins that help cool the engine during use.

Common reasons to replace the flywheel are a sheared keyway (where the flywheel mounts to the crankshaft), damage to the cooling fins, or damage to the starter pawls and/or springs.

This article provides step-by-step instructions for removing and installing the flywheel assembly on a Ryobi string trimmer.

Let's get started.

  REMOVING THE FLYWHEEL [top] 1. Remove the rear cover.

Remove the (4) screws from the rear cover.

Remove the rear cover from the engine.

  2. Remove the carburetor.

Drain any excess fuel from the fuel tank prior to servicing the carburetor or the fuel lines.

Remove the (2) screws from the carburetor assembly.

Remove the choke plate and choke assembly from the carburetor.

Disconnect the throttle cable from the carburetor (this is accomplished using a lift-and-twist motion).

Remove the (2) fuel lines from the carburetor. These lines should pull away from the carburetor inlets relatively easily (by hand); however, small pliers may be used as necessary to disconnect the fuel lines from the carburetor.

Remove the carburetor from the engine.

    3. Disconnect the clutch housing and shaft from the engine.

Remove the (4) screws from the clutch housing.

Remove the clutch housing and shaft from the engine. (The throttle cable should also slide freely from the opening in the engine housing.)

  4. Bind the engine.

This step effectively binds the engine, which facilitates the removal of key components (described in subsequent steps).

Disconnect the spark plug boot from the spark plug.

Use a spark plug wrench (or socket) to loosen the spark plug.

Remove the spark plug from the engine.

Insert the end of an old starter rope (or similar rope) into the engine cylinder (through the spark plug hole). Continue feeding the rope into the cylinder until the piston is unable to move.

  5. Remove the clutch drum.

Loosen the internal screw on the clutch drum using a Phillip's screwdriver (loosen the screw until the clutch drum disengages the spindle; it is not usually necessary to remove the screw entirely).

Remove the clutch drum from the spindle.

  6. Remove the clutch assembly.

Cover the clutch assembly with a shop rag to prevent damage during removal.

Use adjustable pliers to loosen the clutch assembly.

Remove the clutch assembly from the spindle.

  7. Remove the starter assembly.

Remove the (5) screws from the starter assembly. Four of the screws secure the starter to the engine; one screw secures the plastic base.

Gently lift the starter assembly away from the engine. (At this point, the assembly will remain tethered to the engine via the primary ignition wire.)

Use long-nosed pliers to disconnect the ignition wire from the ignition.

Remove the starter assembly from the engine.

  8. Remove the flywheel.

Remove the flywheel spacer from the crankshaft.

Grasp the flywheel and raise the entire engine assembly slightly above the work surface.

Continue holding the flywheel securely with one hand, while striking the end of the crankshaft with a rubber mallet. Repeat this step until the flywheel disengages the crankshaft and engine.

Remove the flywheel assembly from the engine.

Use a pick or small screwdriver to gently pry the woodruff key from the base of the crankshaft.

Remove the woodruff key from the crankshaft.

    INSTALLING THE NEW FLYWHEEL [top] 9. Install the flywheel.

Install the new woodruff key into the slot on the crankshaft.

Tap the woodruff key lightly to seat it into place.

Install the new flywheel onto the crankshaft spindle, ensuring alignment of the keyway with the woodruff key.

Use a rubber mallet to tap lightly around the surface of the flywheel (not the spindle). It is not necessary to completely secure the flywheel with the mallet; just tap it enough to ensure that the internal components engage and seat properly. Installation of the clutch assembly (in subsequent steps) will secure the flywheel to the crankshaft.

  REASSEMBLING THE UNIT [top] 10. Reinstall the starter assembly.

Slide the spacer onto the crankshaft.

Connect the ignition wire to the ignition coil.

Install the starter assembly onto the crankshaft; tuck the ignition wires into the channel on the starter housing as you perform this step.

Align the starter assembly with the mounting holes on the engine.

Hold the starter assembly in place while pulling gently on the starter rope. This will engage the starter pawls and ensure proper alignment.

Secure the starter assembly to the engine with the (4) screws.

Install the plastic base.

Secure the plastic base with the (1) screw.

  11. Reinstall the clutch.

Install the clutch washer.

Thread the clutch onto the spindle until it is hand-tight.

Place a shop rag over the clutch assembly to prevent damage during installation.

Use adjustable pliers to secure the clutch to the engine.

  12. Reinstall the clutch drum.

Install the small spacer washer onto the spindle.

Install the clutch drum onto the clutch.

Secure the clutch drum to the spindle with the internal screw.

  13. Reinstall the spark plug.

Remove the binding (starter rope) from the cylinder.

Install the spark plug into the cylinder.

Use a spark plug wrench (or socket) to secure the spark plug.

Replace the spark plug boot.

    14. Reconnect the upper shaft and clutch drum housing to the engine.

Thread the throttle cable through the engine housing and through the opening on the carburetor mounting assembly.

Reconnect the upper shaft and clutch drum housing to the engine.

Secure the upper shaft and clutch drum housing with the (4) screws.

  15. Reinstall the carburetor.

Install the carburetor gasket.

Install the throttle cable onto the throttle linkage of the carburetor.

Install the incoming fuel line to the lower carburetor inlet.

Install the (primer) fuel line to the upper carburetor inlet.

Install the carburetor mounting screws onto the choke plate and lever.

Secure the carburetor (and choke plate) to the engine with the (2) screws. Note that the choke lever and the wavy washer must be properly aligned before tightening the upper screw.

  16. Reinstall the rear cover.

Reinstall the rear cover onto the engine.

Secure the rear cover with the (4) screws.

You don't have to leverage your savings to level your lawns. As you just learned, repairing your own equipment is easy when you follow our step-by-step guides. Not only did you restore trimmer functionality at a fraction of the cost of replacement; you have taken the edge off of future repairs, wherever you may find them.

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