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16

Bump Knob

MAINTENANCE AND REPAIR INSTRUCTIONS (Continued)

LINE INSTALLATION 

The trimming line may be replaced by two different meth-
ods - rewinding the existing reel or installing a prewound
reel. 

REWINDING THE EXISTING REEL

To rewind the existing reel you must:

1. Check for the correct line size.
2. Remove the existing reel and spring.
3. Wind the existing reel with the new line.
4. Reinstall the existing reel and spring.

The Correct Line to Use

WARNING

Always use genuine Monoflail® replacement line.

Do not use metal-reinforced line.

It is very important to use the correct size line. A line with

diameter of 2.41 mm (.095 in) must be used

The

engine may overheat and fail if you use a larger line.

Removing the Existing Reel

1. Hold the outer spool with one hand and unscrew the

Bump Knob 

clockwise 

(Fig. 26). Inspect the captured

bolt inside the Bump Knob to make sure it moves
freely. Replace the Bump Knob if it is damaged.

2. Remove the inner reel (Fig. 27). 

3. Use a clean cloth to clean the inner surface of the

outer spool (Fig. 28). 

NOTE:

Always clean the inner reel, outer spool,
and shaft before reassembling the 
bump head.

Fig. 27

Fig. 28

Fig. 26

4. Check the indexing teeth on the inner reel and outer

spool for wear (Fig. 29). If necessary, deburr or replace
the reel and spool.

Fig. 29

Inner Reel

Summary of Contents for 990r

Page 1: ...1 MODEL NO 990r IMPORTANT MANUAL DO NOT THROW AWAY 990r OPERATOR S MANUAL ...

Page 2: ... need to order parts PRODUCT REFERENCES ILLUSTRA TIONS AND SPECIFICATIONS All information illustrations and specifications in this man ual are based on the latest product information available at the time of printing We reserve the right to make changes at any time without notice INTRODUCTION TABLE OF CONTENTS SERVICE INFORMATION Service on this power equipment within and after the warranty period...

Page 3: ...e the trimmer at least 3 m 10 ft from the fueling point before starting the engine Thoroughly inspect the trimmer for loose or damaged parts before each use Do not use until adjustments or repairs are made Avoid accidental starting Be in the starting position whenever pulling the starting rope Keep all bystanders especially children and pets at least 10 m 33 ft away from the area Carefully inspect...

Page 4: ...l Always stop the engine when cutting is delayed or when walking from one cutting location to another Use only genuine replacement parts when servicing this trimmer These parts are available from your authorized dealer The use of non standard parts or other accessories or attachments not designed for this trimmer could result in serious injury to the user or damage to the trimmer Do not operate th...

Page 5: ...se severe eye injury and hearing loss Wear ear and eye protection when operating this unit FOR SERVICE INFORMATION CALL USA 1 800 345 8746 CANADA 1 800 265 6778 IGNITION POWER SWITCH ON START RUN IGNITION POWER SWITCH OFF OR STOP INDICATES OIL Refer to operator s manual for the proper type of oil UNLEADED FUEL Always use clean fresh unleaded fuel SIGNIFICATION SYMBOL SAFETY AND INTERNATIONAL SYMBO...

Page 6: ...t operate without guard in place Keep away from rotating cutter BRUSHCUTTERS REPLACE DULL BLADE Do not sharpen the brush blade Sharpening the blade can cause the blade tip to break off while in use This can result in severe personal injury BRUSHCUTTER SAFETY Warning Thrown objects and rotating cutter can cause severe injury Keep bystanders especially children and pets at least 10 m 30 feet away fr...

Page 7: ...e Position Decal Clamp Assembly Fig 2 Fig 1 INSTALLING THE SHOULDER STRAP Your unit is equipped with a shoulder strap pad To install the pad onto the shoulder strap use the following instruc tions 1 Wrap the end of the strap over a blunt object i e ruler Fig 3 2 Push the strap through the pad Fig 3 Remove the object Fig 3 Fig 5 To install the shoulder strap use the following instructions 1 Take th...

Page 8: ... Cover 4 Install the blade washer and lock nut Insert the locking rod into the locking rod slot Fig 7 Make sure that the blade stays flat against the washer while tightening the lock nut counterclockwise until it is finger tight 5 If you have a torque wrench tighten the lock nut to 225 250 in lb 25 3 28 1 N m while holding the locking rod in the locking rod slot Fig 7 If you do not have a torque w...

Page 9: ... t lined up correctly refer to Fig 7 for reassembly Blade Locating Mark Fig 10 INSTALLING THE LINE SPOOL 1 Install the blade guard over the brush blade Insert the locking rod into the locking rod slot Loosen the lock nut by turning it clockwise Fig 7 2 Remove the lock nut retaining washer and brush blade 3 Make sure that you have all of the necessary parts to install the line spool Fig 6 4 Insert ...

Page 10: ...er Fig 12 Installing the Lower Attachment Boom 1 Loosen the wing screws This will allow the lower boom to be inserted into the coupler Fig 12 2 Remove the protective cover or hanger from the lower attachment boom Push the lower attachment boom into the coupler Fig 13 3 Before locking the release button into the coupler rotate the boom 90 degrees then rotate the lower boom back 90 degrees This will...

Page 11: ...ore adding more oil NOTE DO NOT ADD OIL TO THE FUEL THIS ENGINE IS CERTIFIED TO OPERATE ON UNLEADED GAS ONLY NOTE BE SURE TO READ THESE INSTRUCTIONS CAREFULLY BEFORE ATTEMPTING TO START OR OPERATE THIS UNIT Using old or improper oil or fuel can cause engine damage This type of damage will void the engine warranty RECOMMENDED OIL TYPE Using the proper type and weight of oil in the crankcase is extr...

Page 12: ...orrosion and minimize the for mation of gum deposit Add 23 ml 0 8 oz per gallon of fuel per instructions on container NEVER add fuel addi tives directly to the unit s fuel tank Using a fuel additive can keep fuel fresh for up to six 6 months OIL FUEL INFORMATION Continued NOTE Make sure the O ring is in place on the oil fill plug when checking and changing the oil NOTE To prevent extensive engine ...

Page 13: ...THE PARTIAL POSITION Fig 21 PULL THE STARTER ROPE QUICKLY UNTIL THE ENGINE STARTS no more than 5 pulls See Fig 22 6 If the engine does not start repeat steps 2 to 5 7 RUN THE ENGINE FOR 30 SECONDS WITH THE THROTTLE LEVER FULLY SQUEEZED Fig 20 TO WARM UP PLACE THE CHOKE LEVER IN THE RUN POSITION Fig 21 NOTE In colder weather run the engine for 2 to 3 minutes to warm up 8 TO STOP THE ENGINE PUT THE ...

Page 14: ... mm 1 in of trimming line is released A blade in the line guard will cut the line to the proper length if excess line is released For best results tap the head on bare ground or hard soil If line release is attempted in tall grass the engine may stall DECORATIVE TRIMMING Decorative trimming is accomplished by removing all vegetation around trees posts fences etc Use a 30 degree angle when trimming...

Page 15: ... MAINTENANCE SCHEDULE These required maintenance procedures should be performed at the frequency stated in the table They should also be included as part of any seasonal tune up Fill fuel tank Check oil level Page 11 Pages 10 11 MAINTENANCE AND REPAIR INSTRUCTIONS Every 50 Hours Check spark plug condition and gap Check rocker arm to valve clearance Check spark arrester screen Page 22 Page 22 Page ...

Page 16: ...ery important to use the correct size line A line with a diameter of 2 41 mm 095 in must be used The engine may overheat and fail if you use a larger line Removing the Existing Reel 1 Hold the outer spool with one hand and unscrew the Bump Knob clockwise Fig 26 Inspect the captured bolt inside the Bump Knob to make sure it moves freely Replace the Bump Knob if it is damaged 2 Remove the inner reel...

Page 17: ...ISTING REEL 3 Follow the instructions in REINSTALLING THE REEL Winding the Existing Reel 1 Take approximately 12 7 m 50 ft of new trimming line loop it into two equal lengths Insert each end of the line through one of the two holes in the inner reel Fig 30 Pull the line so that the loop is as small as possible 2 Wind the lines in even and tight layers onto the reel Fig 31 Wind the line in the dire...

Page 18: ...has cooled 1 Check the gear housing for lubricant every 50 hours of operation 2 To check the lubricant level remove the fill plug Fig 34 The lubricant should be up to the bottom edge of the check hole If it is low bring the level up with a good quality lithium based 2 multi purpose grease 3 Reinstall the fill plug and tighten securely to prevent leakage Fig 34 Fill Plug ...

Page 19: ...install the air filter cover AIR FILTER MAINTENANCE 2 Remove the air filter Fig 36 5 Squeeze the filter to spread the oil Fig 39 MAINTENANCE AND REPAIR INSTRUCTIONS Continued 3 Wash the filter in detergent and water Fig 37 Rinse the filter thoroughly and allow it to dry 4 Apply enough clean SAE 30 oil to saturate the filter Fig 38 Fig 38 Fig 39 Fig 37 Fig 36 6 Reinstall the filter see Fig 36 air f...

Page 20: ... the carburetor The resulting symptoms are often mistaken for an out of adjustment carburetor Therefore check the condition of the air filter before adjusting the carburetor Refer to Air Filter Maintenance If the following conditions are experienced it may be nec essary to adjust the carburetor The engine will not idle The engine hesitates or stalls on acceleration The loss of engine power that is...

Page 21: ...ting bolts from the cylinder Fig 42 8 Final Idle Speed Adjustment Adjust the idle speed by turning the idle speed screw in clockwise or out counterclockwise until the cutting head does not rotate Do not squeeze the throttle trigger when adjusting the idle speed screw Definition of Optimum Setting for Idle Speed Mixture and High Speed Mixture Adjustments Always set the idle speed mixture needle and...

Page 22: ...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 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 bef...

Page 23: ...rk plug Correct air gap is 025 in 0 635 mm Remove plug after every 50 hours of operation and check its condition Allow the engine to cool before removing the spark plug 1 Stop the engine and pull the wire off of the spark plug 2 Clean around the spark plug and remove it from the cylinder head NOTE Replace a cracked fouled or dirty spark plug Do not sand blast scrape or clean electrodes because the...

Page 24: ...n specification adjust as follows a Turn the adjusting nut Fig 52 using an 5 16 in 8 mm wrench or nut driver To increase the rocker arm to valve clearance turn the adjusting nut counterclockwise To decrease the rocker arm to valve clearance turn the adjusting nut clockwise b Recheck the clearance with a flat feeler gauge and readjust as necessary Fig 49 7 Reinstall the rocker arm cover using a new...

Page 25: ...d for more than 60 days 2 Start the engine and allow it to run until it stalls This ensures that all fuel has been drained from the carbu retor Fig 53 DRIVE SHAFT CUTTING HEAD Drive Shaft Steel 1 4 Drive Shaft Housing Steel Tube Split Boom Operating Weight 7 78 kg 17 2 lbs Throttle Control Finger Tip Trigger Shoulder Strap with Pad Standard Line Spool Diameter 102 mm 4 in Trimming Line Diameter 2 ...

Page 26: ... procedure Pages 18 19 Dirty spark arrestor screen Clean or replace screen Carburetor misadjusted Adjust carburetor Pages 16 17 Not enough fuel in fuel tank Fill fuel tank Cutting Head Will Not Advance Cutting head out of line Refill with new cutting line Pages 13 14 Line Inner reel bound up Replace inner reel Pages 13 14 Cutting head dirty Clean inner reel and outer spool Pages 13 14 Indexing tee...

Page 27: ...ding your warranty rights and responsibilities you should call 1 800 345 8746 MANUFACTURER S WARRANTY COVERAGE The warranty period begins on the date the engine or equipment is delivered to the retail purchaser The manufacturer warrants to the initial owner and each subsequent purchaser that the engine is free from defects in material and workmanship which cause the failure of a warranted part for...

Page 28: ...which are either incompatible with the RYOBI Product or adversely affect its operation performance or durability In addition this warranty does not cover A Tune ups Spark Plugs Carburetor Adjustments Filters B Wear items Bump Knobs Outer Spools Cutting Line Inner Reels Starter Pulley Starter Ropes RYOBI reserves the right to change or improve the design of any RYOBI Product without assuming any ob...

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