Troy-Bilt TB590 EC, Operator'S Manual

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REPLACING THE SPARK PLUG
Use a replacement part number 753-05784 or Champion® RDZ4H spark
plug. The correct air gap is 0.025 in. (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. Remove the six (6) screws on the back
of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 48).
2. Grasp the plug wire firmly and pull the cap from the spark plug.
3. Clean dirt from around the spark plug.
Remove the spark plug from the cylinder
head by turning a 5/8 in. socket
counterclockwise.
4. Replace cracked, fouled or dirty spark plug.
Set the air gap at 0.025 in. (0.635 mm) using a feeler gauge (Fig. 48).
5. Install a correctly-gapped spark plug in the cylinder head. Turn the 5/8 in.
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.
ROCKER ARM CLEARANCE
This SERVICE requires disassembly of the engine. If you feel unsure or
unqualified to perform this, take the unit to an authorized service center.
• The engine must be cold when checking or adjusting the valve clearance.
• This task should be performed inside, in a
clean, dust free area.
1. Remove the six (6) screws on the back of the
engine cover with a Flat-head or T-25 Torx
screwdriver (Fig. 44).
2. Disconnect the spark plug wire.
3. Clean dirt from around the spark plug.
Remove the spark plug from the cylinder
head by turning a 5/8 in. socket
counterclockwise.
4. Remove the engine cover (Fig. 44).
5. Clean dirt from around the rocker arm cover.
Remove the screw holding the rocker arm
cover with a large flat blade screwdriver or
Torx T-25 bit (Fig. 45). Remove the rocker arm
cover and gasket.
6. Pull the starter rope slowly to bring the piston
to the top of its travel, (known as top dead
center). Check that:
• The piston is at the top of its travel while
looking in the spark plug hole (Fig. 45).
• Both rocker arms move freely, and both
valves are closed.
If these statements are not true, repeat this step.
7. Slide the feeler gauge between the rocker arm
and the valve return spring. Measure the
clearance between the valve stem and rocker
arm (Fig. 46). Measure both the intake and
exhaust valves.
The recommended clearance for both intake
and exhaust is
.003 – .006 in. (.076 – 0.152
mm) . Use a standard automotive .005 in.
(0.127 mm) feeler gauge. The feeler gauge
should slide between the rocker arm and valve
stem with a slight amount of resistance,
without binding. See Figures 46 and 47.
8. If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 mm) wrench or nut driver (Fig. 47).
• To increase clearance, turn the adjusting nut counterclockwise.
• To decrease clearance, turn the adjusting nut clockwise.
b. Recheck both clearances, and adjust as necessary.
MAINTENANCE AND REPAIR INSTRUCTIONS
Valve Stem
Fig. 47
Adjusting Nut
Feeler
Gauge
Rocker Arm
0.003–0.006 in.
(0.076–0.152 mm)
Fig. 44
View Of The Rear Engine Cover
Fig. 45
Rocker Arm Cover
Fig. 46
Adjustment
Nuts
Intake
Exhaust
Rocker
Arms
Spark Plug
Hole
Screws Screws
WARNING:
Do not sand blast,
scrape or clean electrodes. Grit in the
engine could damage the cylinder.
9
IDLE SPEED ADJUSTMENT
The idle speed of the engine is adjustable. An idle adjustment screw is
between the air filter cover and the engine starter housing (Fig. 43).
NOTE: Careless adjustments can seriously
damage your unit. An authorized service
dealer should make carburetor adjustments.
If, after checking the fuel 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 in between the air filter cover and the
engine cover (Fig. 43). Turn the idle speed screw in, clockwise, 1/8 of a turn
at a time (as needed) until the engine idles smoothly.
NOTE: The cutting attachment should not rotate when the engine idles.
3. If the cutting attachment rotates when the engine idles, turn the idle speed
screw counterclockwise 1/8 of a turn at a time (as needed), to reduce idle
speed.
Checking the fuel, 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.
WARNING:
The cutting attachment may spin during idle speed
adjustments. Wear protective clothing and observe all safety
instructions to prevent serious personal injury.
Fig. 43
Idle Adjustment Screw
ROCKER ARM CLEARANCE
9. Reinstall the rocker arm cover using a new gasket. Torque the screw to
20–30 in•lb (2.2–3.4 N•m) .
10.Check the spark plug and reinstall. See Replacing the Spark Plug.
11.Replace the spark plug wire.
12.Reinstall the engine cover. Check alignment of the cover before tightening
the screws. Tighten screws.
Fig. 48
0.025 in.
(0.635 mm)
CLEANING
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.
STORAGE
• Never store the unit with fuel in the tank where fumes may reach an open
flame or spark.
• Allow the engine to cool before storing.
• Lock up the unit to prevent unauthorized use or damage.
• Store the unit in a dry, well-ventilated area.
• Store the unit out of the reach of children.
Short Term Storage (1-2 weeks)
1. Store the unit in a horizontal position. If this is not possible, store the unit
vertically with the engine at the top.
Long Term Storage
1. Drain all gasoline from the gas tank into a container. Do not use gas that
has been stored for more than 30 days. Dispose of the old gasoline in
accordance with federal, state and local regulations.
2. Start the engine and allow it to run until it stalls. This ensures that all
gasoline has been drained from the carburetor.
3. Allow the engine to cool. Remove the spark plug and put 5 drops of high
quality motor 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. Change the oil, referring to Changing the Oil . Dispose of the old oil in
accordance with federal, state and local regulations.
5. Thoroughly clean the unit and inspect for any loose or damaged parts.
Repair or replace damaged parts and tighten loose screws, nuts or bolts.
The unit is ready for storage.
WARNING:
To avoid serious personal injury, always turn the
unit off and allow it to cool before cleaning or servicing it.
CLEANING AND STORAGE