Ryobi 990r Inspection and Cleaning, Checking Spark Arrester Screen, Muffler Reassembly, Cover

MAINTENANCE AND REPAIR INSTRUCTIONS (Continued)

Inspection and Cleaning

Inspect the inlet port of the muffler and outlet port of the cylinder for excessive carbon build-up. Excessive deposits around the exhaust ports or exhaust holes will cause poor engine performance.

If carbon build-up cannot be cleaned, replace the muffler.

Inspect the muffler mounting holes for elongation. Replace the muffler if the holes are elongated.

Checking Spark Arrester Screen

This unit is equipped with a spark arrester screen. Every 50 hours of operation, check the spark arrester screen for debris and / or deposits.

WARNING

Make sure the muffler is cool before checking the spark arrester screen to prevent injury.

Check the spark arrester screen as follows:

1.Remove the screw (Fig. 44).

2.Remove the cover (Fig. 44).

3.Push the spark arrester screen out of the cover.

	Spark Arrester
Cover	Screen
	Screw

Fig. 44

4.Inspect the spark arrester screen.

If the screen is clean, reinstall the screen, cover and screw. If the screen is plugged, replace it.

5.Torque the screw to 15-20 in•lb (1.7-2.2 N•m).

Muffler Reassembly

1.Install a new muffler gasket and place the muffler baffle in place (Fig. 45).

2.Install the muffler with the three (3) mounting bolts. Install the lower bolt first to ease the installation of the top two (2) bolts (Fig. 46).

NOTE: The 5 mm nut must be held in the slot next to the spark plug before installing the top rear muffler bolt.

NOTE: Be careful not to crossthread the muffler mounting bolts.

Torque the muffler mounting bolts to 40-45 in•lb

(4.5-5.0 N•m).

Muffler Mounting

Bolt

Muffler Mounting

Bolt

Fig. 45

Muffler

Muffler Gasket

Fig. 46

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