Maintenance & Repair Instructions - Troy-Bilt TB70SS Operator's Manual

SPARK ARRESTOR MAINTENANCE
1. Remove air filter/muffler cover. Refer to Removing the Air
Filter/Muffler Cover.
2. Locate the muffler, but do not remove it. Find the screw on
the bottom of the muffler (Fig. 31). Remove the screw using
either a torx #20 or flat blade screwdriver.
WARNING:
If the spark arrestor hood and
spark arrestor screen are not tightened securely,
they could fall off causing damage to the unit
and possible serious personal injury.
3. Carefully pry up the left side spark arrestor hood. Two tabs
act as hinges on the right side of the hood. Flip open the
spark arrestor hood like a door and then pull its tabs out of
the muffler slots.
4. Using a small flat blade screwdriver, carefully pry the spark
arrestor screen out from the inside of the spark arrestor
hood.
5. Clean the spark arrestor screen with a wire brush. Replace it if it
is damaged, or if you are unable to clean it thoroughly.
6. Reinstall the spark arrestor screen snugly back into the spark
arrestor hood.
7. Reinstall the two hood tabs into the two muffler slots and
flip the spark arrestor hood closed.
8. Replace the screw you removed in Step 2 and tighten it securely.
9. Reinstall the air filter/muffler cover.
WARNING:
The cutting attachment will not
spin during idle speed adjustments. Wear
protective clothing and observe all safety
instructions to prevent serious personal injury.
CARBURETOR ADJUSTMENT
The idle speed of the engine is adjustable through the air
filter/muffler cover (Fig. 32).
NOTE: Careless adjustments can seriously damage your
unit. An authorized service dealer should make
carburetor adjustments.
Check Fuel Mixture
Old and/or improperly mixed fuel is usually the reason for improper unit
performance. Drain and refill the tank with fresh, properly-mixed fuel prior
to making any adjustments. Refer to Oil and Fuel Information.
Clean Air Filter
The condition of the air filter is important to the operation of the unit. A dirty
air filter will restrict air flow and change the air/fuel mixture. This is often
mistaken for an out of adjustment carburetor. Check the condition of the air filter before adjusting the idle speed screw.
Refer to Air Filter Maintenance.
Adjust Idle Speed Screw
If, after checking the fuel mixture and cleaning the air filter, the engine still will not idle, adjust the idle speed
screw as follows:
1. Start the engine and let it run at a high idle for a minute to
warm up. Refer to Starting/Stopping Instructions.
2. Release the throttle trigger and let the engine idle. If the engine
stops, insert a small phillips screwdriver into the hole in the air
filter/muffler cover (Fig. 32). Turn the idle speed screw in,
clockwise, 1/8 of a turn at a time (as needed) until the engine
idles smoothly.
3. If the engine appears to be idling too fast, turn the idle speed
screw counterclockwise 1/8 of a turn at a time (as needed),
to reduce idle speed.
Checking the fuel mixture, cleaning the air filter, and adjusting the
idle speed should solve most engine problems. If not and all of the
following are true:
• the engine will not idle
• the engine hesitates or stalls on acceleration
• there is a loss of engine power
Have the carburetor adjusted by an authorized service dealer.
REPLACING THE SPARK PLUG
Use a Champion RDJ7Y spark plug, or equivalent. The correct air gap is 0.025 inch (0.635 mm). Remove the
plug after every 25 hours of operation and check its condition.
1. Stop the engine and allow it to cool. Grasp the plug wire
firmly and pull it from the spark plug.
2. Clean around the spark plug. Remove the spark plug from
the cylinder head by turning a 5/8-inch socket
counterclockwise.
WARNING:
Do not sand blast, scrape or clean
electrodes. Grit in the engine could damage the
cylinder.
3. Replace a cracked, fouled or dirty spark plug. Set the air
gap at 0.025 in. (0.635 mm) using a feeler gauge (Fig. 33).
4. Install a correctly-gapped spark plug in the cylinder head. Tighten by turning the 5/8-inch socket
clockwise until snug.
If using a torque wrench torque to:
110-120 in.•lb. (12.3-13.5 N•m)
Do not over tighten.
CLEANING
WARNING:
To avoid serious personal injury, always turn your trimmer off and allow it to
cool before you clean or service it.
Use a small brush to clean off the outside of the unit. Do not use strong detergents. Household cleaners that
contain aromatic oils such as pine and lemon, and solvents such as kerosene, can damage plastic housing or
handle. Wipe off any moisture with a soft cloth.
6
MAINTENANCE AND REPAIR INSTRUCTIONS
Fig. 28
Fig. 29
Fig. 30
Engine
Slots
Spark Muffler
Arrestor
Hood
Spark Arrestor
Screw
Tabs Screen
Fig. 31
Idle Speed Screw
Fig. 32
0.025 in.
(0.635 mm)
Fig. 33
STORAGE
• Never store a fueled unit where fumes may reach an open flame or spark.
• Allow the engine to cool before storing.
• Store the unit locked up to prevent unauthorized use or damage.
• Store the unit in a dry, well-ventilated area.
• Store the unit out of the reach of children.
LONG TERM STORAGE
If you plan on storing the unit for an extended time, use the following storage procedure:
1. Drain all fuel from the fuel tank into a container with the same 2-cycle fuel mixture. Do not use fuel
that has been stored for more than 60 days. Dispose of the old fuel/oil mix in accordance to
Federal, State and Local regulations.
2. Start the engine and allow it to run until it stalls. This ensures that all fuel has been drained from the carburetor.
3. Allow the engine to cool. Remove the spark plug and put 1 oz. (30 ml) of any high quality motor oil or
2-cycle oil into the cylinder. Pull the starter rope slowly to distribute the oil. Reinstall the spark plug.
NOTE: Remove the spark plug and drain all of the oil from the cylinder before attempting to start the
trimmer after storage.
4. Thoroughly clean the unit and inspect it for any loose or damaged parts. Repair or replace
damaged parts and tighten loose screws, nuts or bolts. The unit is ready for storage.
TROUBLESHOOTING
ENGINE WILL NOT START
CAUSE
On/Off control in the OFF position
Empty fuel tank
Primer bulb wasn't pressed enough
Engine is flooded
Old or improperly mixed fuel
Fouled spark plug
Plugged spark arrestor
ENGINE WILL NOT IDLE
CAUSE
Air filter is plugged
Old or improperly mixed fuel
Improper carburetor adjustment
ENGINE WILL NOT ACCELERATE
CAUSE
Old or improperly mixed fuel
Improper carburetor adjustment
Cutting attachment bound with grass
Dirty air filter
Plugged spark arrestor
ENGINE LACKS POWER OR STALLS WHEN CUTTING
CAUSE
Old or improperly mixed fuel
Improper carburetor adjustment
Fouled spark plug
Plugged spark arrestor
CUTTING ATTACHMENT WILL NOT ADVANCE LINE
CAUSE
Cutting attachment bound with grass
Cutting attachment out of line
Inner reel bound up
Cutting head dirty
Line welded
Line twisted when refilled
Not enough line is exposed
CUTTING LINE ADVANCES UNCONTROLLABLY
CAUSE
Oil, cleaner or lubricant in cutting head
If further assistance is required, contact your authorized service dealer.
ACTION
Turn On/Off control to ON
Fill fuel tank with properly mixed fuel
Press primer bulb fully and slowly 10 times
Squeeze the trigger and pull the starter rope
Drain gas tank and add fresh fuel mixture
Replace or clean the spark plug
Clean or replace spark arrestor
ACTION
Replace or clean the air filter
Drain gas tank and add fresh fuel mixture
Adjust according to the Carburetor Adjustments
section
ACTION
Drain gas tank and add fresh fuel mixture
Take to an authorized service dealer for an
adjustment
Stop the engine and clean the cutting attachment
Clean or replace the air filter
Clean or replace spark arrestor
ACTION
Drain gas tank and add fresh fuel mixture
Take to an authorized service dealer for an
adjustment
Replace or clean the spark plug
Clean or replace spark arrestor
ACTION
Stop the engine and clean cutting attachment
Refill with new line
Replace the inner reel
Clean inner reel and outer spool
Disassemble, remove the welded section and
rewind
Disassemble and rewind the line
Push the bump knob and pull out line until 4 inches
(102 mm) of line is outside of the cutting attachment
ACTION
Clean and thoroughly dry the cutting head