Cleaning And Storage; Troubleshooting Chart; Specifications - CubCadet ST4125 Manual Del Operador

MAINTENANCE AND REPAIR INSTRUCTIONS
AIR FILTER MAINTENANCE
WARNING:
To avoid serious personal injury, always turn the unit off and allow it to cool before you
clean or service it.
Cleaning the Air Filter
Failure to maintain your air filter properly can result in poor performance or can cause
permanent damage to your engine.
1. Open the air filter cover. Push the tab on the left side of the cover inward. Then
pull the air filter cover out and to the right (Fig. 26).
NOTE: It may be necessary to remove the fuel cap to completely remove the air
filter cover.
2. Remove the air filter (Fig. 26).
3. Wash the filter in detergent and water. Rinse the filter thoroughly and allow it to dry.
4. Apply enough clean SAE 30 motor oil to lightly coat the filter.
5. Squeeze the filter to spread and remove excess oil.
6. Replace the filter (Fig. 26).
NOTE: If the unit is operated without the air filter, you will VOID the warranty.
7. Reinstall the air filter cover. Position the hooks on the right side of the air filter cover into the slots at the right side
of the back plate (Fig. 26).
NOTE: It may be necessary to remove the fuel cap to completely replace the air filter cover.
8. Swing the cover to the left until the tab on the air filter cover snaps into place in the slot on the back plate (Fig. 26).
9. Replace the fuel cap if you have removed it.
IDLE SPEED ADJUSTMENT
WARNING:
The cutting attachment may spin during idle speed adjustments. Wear protective clothing
and observe all safety instructions to prevent serious personal injury.
The idle speed of the engine is adjustable. An idle adjustment screw is between the
air filter cover and the engine starter housing (Fig. 27).
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. 27). 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.
ROCKER ARM CLEARANCE
WARNING:
To avoid serious personal injury, always turn the unit off and allow it to cool before you
clean or service it.
This service requires disassembly of the engine. If
feeling unsure or unqualified to perform this service,
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 five (5) screws with a Flat-head or
T-20 Torx screwdriver and the one T-25 screw
(Fig. 28).
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. 28).
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. 29). 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. 29).
• 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. 30). 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 30 and 31.
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. 31).
• 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 791-180852B spark plug. The correct air gap is 0.025 in. (0.635 mm).
1. Stop the engine and allow it to cool. Remove the five (5) screws with a Flat-head or T-20 Torx screwdriver and the
one T-25 screw (Fig. 28).
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. 32).
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.
4
Air Filter
Fig. 26
Idle Adjustment Screw
Fig. 27
View Of The Rear Engine Cover
Rocker Arm
Cover
Screws Screws
Spark
Plug Hole
T-25 Screws
Fig. 28 Fig. 29
Adjustment
Nuts
Rocker Intake
Arms
0.003–0.006 in.
(0.076–0.152 mm)
Exhaust
Fig. 30 Fig. 31
0.025 in.
(0.635 mm.)
Fig. 32
CLEANING
WARNING:
cleaning or servicing it.
Use a small brush to clean off the outside of the unit. Do not use strong detergents. Household cleaners that contain
Air Filter Cover
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.
Tab
• 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.
CAUSE
ENGINE WILL NOT START
Empty fuel tank
Primer bulb wasn't pressed enough
Old fuel (over 30 days)
Fouled spark plug
ENGINE WILL NOT IDLE
Air filter is plugged
Old fuel (over 30 days)
Improper idle speed
ENGINE WILL NOT ACCELERATE
Old fuel (over 30 days)
Cutting attachment bound with grass
Dirty air filter
ENGINE LACKS POWER OR STALLS WHEN CUTTING
Old fuel (over 30 days)
Fouled spark plug
If further assistance is required, contact an authorized service dealer.
UNIT*
Engine Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air-Cooled, 4-Cycle
Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 cu. in. (26.2 cc)
Feeler
Clutch Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Centrifugal
Gauge
Operating RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,200+ rpm
Idle Speed RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,800 - 3,600 rpm
Valve clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.003–0.006 in. (0.076–0.152 mm)
Spark Plug Gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.025 inch (0.635 mm)
Valve Stem
Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAE 30 Oil
Crankcase Oil Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.04 oz (90 ml)
Fuel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unleaded
Fuel Tank Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 oz (532 ml)
Approximate Unit Weight (No fuel, with handle, shield and cutting attachment) . . . . . . . . . . . . . . . . . . . 14.5 lbs (6.5 kg)
Cutting Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fixed Line Cutting Head
Line Spool Diameter:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 inches (76.2 mm)
Trimming Line Diameter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.105 inches (2.67 mm)
Cutting Path Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 in. (43.18 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.
MAINTENANCE AND REPAIR INSTRUCTIONS
To avoid serious personal injury, always turn the unit off and allow it to cool before
TROUBLESHOOTING
ACTION
Fill fuel tank with fuel
Press primer bulb fully and slowly 10 times
Drain fuel tank and add fresh fuel
Replace or clean the spark plug
Replace or clean the air filter
Drain fuel tank and add fresh fuel
Adjust according to the Idle Speed Adjustment section
Drain fuel tank and add fresh fuel
Stop the engine and clean the cutting attachment
Clean or replace the air filter
Drain fuel tank and add fresh fuel
Replace or clean the spark plug

SPECIFICATIONS