MTD WH25CS - Manual (Page 7)

7
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. 30). Remove the screw using either
a torx #20 or flat blade screwdriver.
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.
CARBURETOR ADJUSTMENT
The idle speed of the engine is adjustable through the air
filter/muffler cover (Fig. 31).
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. 31). 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 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.
Fig. 31
Idle Speed Screw
Fig. 30
Spark Arrestor
Hood
Muffler
Screw
Engine
Spark
Arrestor
Screen Tabs
Slots
WARNING: If the exhaust deflector assembly is not tightened securely, it could fall off
causing damage to the unit and possible serious personal injury.
WARNING: The cutting attachment may spin during idle speed adjustments. Wear
protective clothing and observe all safety instructions to prevent serious personal injury.
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 in. socket counterclockwise.
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. 32).
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
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.
• 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 the unit will be stored 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.
TRANSPORTING
•
Allow the engine to cool before transporting.
• Drain fuel from unit.
• Tighten fuel cap before transporting.
• Secure the unit while transporting.
WARNING: To avoid serious personal injury, always turn your unit off and allow it to
cool before you clean or service it.
WARNING: To prevent serious personal injury, make sure the cutting attachment has
stopped rotating before you turn it off and set it down.
WARNING: Do not sand blast, scrape or clean electrodes. Grit in the engine could
damage the cylinder.
Fig. 32
0.025 in.
(0.635 mm)
If further assistance is required, contact your authorized service dealer.
CAUSE ACTION
Cutting attachment bound with grass Stop the engine and clean cutting attachment
Cutting attachment out of line Refill with new line
Inner reel bound up Replace the inner reel
Cutting head dirty Clean inner reel and outer spool
Line welded Disassemble, remove the welded section and rewind
Line twisted when refilled Disassemble and rewind the line
Not enough line is exposed Push the bump knob and pull out line until 4 inches
(102 mm) of line is outside of the cutting attachment
CAUSE ACTION
Old or improperly mixed fuel Drain gas tank and add fresh fuel mixture
Improper carburetor adjustment Take to an authorized service dealer for an adjustment
Fouled spark plug Replace or clean the spark plug
Plugged spark arrestor Clean or replace spark arrestor
CAUSE ACTION
Empty fuel tank Fill fuel tank with properly mixed fuel
Primer bulb wasn't pressed enough Press primer bulb fully and slowly 10 times
Engine is flooded Squeeze the trigger and pull the starter rope
Old or improperly mixed fuel Drain gas tank and add fresh fuel mixture
Fouled spark plug Replace or clean the spark plug
Plugged spark arrestor Clean or replace spark arrestor
The outside temperature is below 40º F Pull the starter rope up to 10-15 times
The outside temperature is above 90º F Squeeze the throttle control and pull the starter rope
ENGINE WILL NOT START
ENGINE WILL NOT IDLE
ENGINE WILL NOT ACCELERATE
CAUSE ACTION
Air filter is plugged Replace or clean the air filter
Old or improperly mixed fuel Drain gas tank and add fresh fuel mixture
Improper carburetor adjustment Adjust according to the Carburetor Adjustments section
CAUSE ACTION
Old or improperly mixed fuel Drain gas tank and add fresh fuel mixture
Improper carburetor adjustment Take to an authorized service dealer for an adjustment
Cutting attachment bound with grass Stop the engine and clean the cutting attachment
Dirty air filter Clean or replace the air filter
Plugged spark arrestor Clean or replace spark arrestor
CAUSE ACTION
Oil, cleaner or lubricant in cutting head Clean and thoroughly dry the cutting head
TROUBLESHOOTING
CUTTING LINE ADVANCES UNCONTROLLABLY
CUTTING ATTACHMENT WILL NOT ADVANCE LINE
ENGINE LACKS POWER OR STALLS WHEN CUTTING