Ryobi String Trimmer Repair

Press down on the latch on the plastic engine cover while simultaneously pulling the cover away from the engine to reveal the air filter screen. Clean the surface of the screen regularly with a soft bristle brush to keep the engine running properly and for engine longevity. Put back the cover by inserting the tabs on the cover into the slots on the base of the air cleaner assembly. Push the cover against the side of the engine until it snaps into place.

Locate the idle speed adjustment screw behind the plastic engine cover near the air filter. Remove the cover. Turn the screw slightly in a counterclockwise direction with a flat blade screwdriver if the trimmer cutting head spins while the engine is idling. Turn the screw until the head stops spinning and the engine is running smoothly. Replace the cover.

Locate the spark plug on the side of the engine cylinder head. Pull the spark plug wire straight off of the spark plug and push it aside. Press a spark plug wrench onto the end of the plug until it is fully seated. Twist the plug out of the engine in a counterclockwise direction. Check the gap between the grounding strap and the center electrode of the plug with a spark plug gapping tool. Move the grounding strap in the direction needed with the notched end of the spark plug gapping tool so that the gap is .025 inch. Thread the plug back into the engine and tighten it with the spark plug wrench.

Loosen the full filler cap if the engine is running poorly. Replace the cap with a new one, which has a built-in non-replaceable filter, if engine performance improves when the cap is loosened.

Replace the string cutting head by first removing the spool retainer at the base of the head in a counterclockwise direction. Place the retainer aside. Pull the head straight off of the base of the trimmer. Push a new cutting head into place on the trimmer until it is fully seated on the drive shaft. Twist the retainer back into place hand-tight.