Specifications; Replacing The Spark Plug; Troubleshooting - Troy-Bilt TB525CS Operator's Manual

MAINTENANCE AND REPAIR INSTRUCTIONS
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. 37).
• 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. 38). 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 38 and 39.
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. 39).
• To increase clearance, turn the adjusting nut counterclockwise.
• To decrease clearance, turn the adjusting nut clockwise.
b. Recheck both clearances, and adjust as necessary.
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.

REPLACING THE SPARK PLUG

Use a replacement part number 753-05255 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. 40).
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.
WARNING: Do not sand blast, scrape or clean electrodes. Grit in the engine could
damage the cylinder.
4. Replace cracked, fouled or dirty spark plug. Set the air gap at 0.025 in. (0.635 mm.) using a feeler
gauge (Fig. 40).
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.
SPARK ARRESTOR MAINTENANCE
1. Remove the rear engine cover. See Rocker Arm Clearance.
2. With a flat blade screwdriver or Torx T-20 bit and a T-25 bit,
remove the screws attaching the spark arrestor cover to the
muffler (Fig. 41).
3. Pull the tab on the spark arrestor cover out of the muffler.
Remove the spark arrestor cover.
4. Remove the spark arrestor screen from the spark arrestor cover.
5. Clean the spark arrestor screen with a wire brush or replace it.
6. Reinstall the spark arrestor screen, spark arrestor cover and screws.
CLEANING
WARNING:
To avoid serious personal injury, always turn the unit 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.
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.
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 60 days. Dispose of the old gasoline in accordance to 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 to 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.
TRANSPORTING
• Allow the engine to cool before transporting.
• Secure the unit while transporting.
• Drain the gas tank before transporting.
• Tighten gas cap before transporting.
Adjusting Nut Rocker Arm
Feeler
Gauge
0.003–0.006 in.
(0.076–0.152 mm)
Valve Stem
Fig. 39
0.025 in.
(0.635 mm.)
Fig. 40
Muffler
Spark Arrestor
Screen
Diverter
T-25
Screw
Slot
T-20 Screw
Fig. 41

TROUBLESHOOTING

ENGINE WILL NOT START
CAUSE
Empty fuel tank
Primer bulb wasn't pressed enough
Old fuel
Fouled spark plug
Plugged spark arrestor
ENGINE WILL NOT IDLE
CAUSE
Air filter is plugged
Old fuel
Improper carburetor adjustment
ENGINE WILL NOT ACCELERATE
CAUSE
Old fuel
Cutting attachment bound with grass
Dirty air filter
Plugged spark arrestor
ENGINE LACKS POWER OR STALLS WHEN CUTTING
CAUSE
Old fuel
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.

SPECIFICATIONS

ENGINE*
Engine Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air-Cooled, 4-Cycle
Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 cu. in. (29 cc)
Operating RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,800+ rpm
Idle Speed RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,800 - 3,600 rpm
Ignition Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electronic
Ignition Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rocker Switch
Valve clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.003–0.006 in. (0.076–0.152 mm)
Spark Plug Gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.025 inch (0.635 mm)
Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAE 30 Oil
Crankcase Oil Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.04 oz (90 ml)
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unleaded
Carburetor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm, All-Position
Starter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Auto Rewind
Muffler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Baffled with Guard
Throttle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manual Spring Return
Fuel Tank Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 oz (414 ml)
DRIVE SHAFT AND CUTTING ATTACHMENT*
Drive Shaft Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel Tube (EZ-Link™)
Throttle Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Finger-Tip Trigger
Approximate Unit Weight (No fuel, with handle, cutting attachment and shield) 11.5-13.0 lbs (5.2-5.9 kg)
Cutting Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SpeedSpool 2®
Line Spool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bump Line Releaser
Line Spool Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 inches (101.6 mm)
Trimming Line Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .095 inches (2.41 mm)
Cutting Path Diameter, Trimmer Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 inches (43.2 cm)
*All specifications 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.
ACTION
Fill fuel tank with fuel
Press primer bulb fully and slowly 10 times
Drain gas tank and add fresh fuel
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
Adjust according to the Carburetor Adjustments
section or take to an authorized service dealer
for an adjustment
ACTION
Drain gas tank and add fresh fuel
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
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 head 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
7