Maintenance & Repair Instructions - MTD MP425 Operator's Manual

OPERATING INSTRUCTIONS
NOTE: Do not rest the Bump Head™ on the ground while the unit is running.
Some line breakage will occur from:
• Entanglement with foreign matter
• Normal line fatigue
• Attempting to cut thick, stalky weeds
• Forcing the line into objects such as walls or fence posts
TIPS FOR BEST TRIMMING RESULTS
• Keep the cutting head parallel to the ground.
• Do not force the cutting head. Allow the tip of the line to do the cutting, especially along walls. Cutting with more
than the tip will reduce cutting efficiency and may overload the engine.
• Cut grass over 8 inches (200 mm) by working from top to bottom in small increments to avoid premature line wear
or engine drag.
• Cut from right to left whenever possible. Cutting to the left improves the unit's cutting efficiency. Clippings are thrown away
from the operator.
• Slowly move the trimmer into and out of the cutting area at the desired height. Move either in a forward-backward or
side-to-side motion. Cutting shorter lengths produces the best results.
• Trim only when grass and weeds are dry.
• The life of your cutting line is dependent upon:
• Following the trimming techniques
• What vegetation is being cut
• Where vegetation is cut
For example, the line will wear faster when trimming against a foundation wall as
opposed to trimming around a tree.
DECORATIVE TRIMMING
Decorative trimming is accomplished by removing all vegetation around trees, posts, fences and more.
Rotate the whole unit so that the cutting head is at a 30° angle to the ground (Fig. 16).
MAINTENANCE AND REPAIR INSTRUCTIONS
MAINTENANCE SCHEDULE
WARNING:
To prevent serious injury, never perform maintenance or repairs with unit running. Always
service and repair a cool unit. Disconnect the spark plug wire to ensure that the unit cannot start.
Perform these required maintenance procedures at the frequency stated in the table. These procedures should also be
a part of any seasonal tune-up.
NOTE: Some maintenance procedures may require special tools or skills. If you are unsure about these procedures
take your unit to any non-road engine repair establishment, individual or authorized service dealer.
NOTE: Maintenance, replacement, or repair of the emission control devices and system may be performed by any
non-road engine repair establishment, individual or authorized service dealer.
FREQUENCY MAINTENANCE REQUIRED
Every 10 hours Clean and oil air filter
Change 1st 10 hours Change oil
Change oil
Clean spark arrestor
Every 40 hours
Check rocker arm to valve clearance and adjust
Check spark plug condition and gap
LINE INSTALLATION
WARNING:
Never use metal-reinforced line, wire, chain or rope. These can break off and become
dangerous projectiles.
This section covers both SplitLine® and standard single line installation.
Always use original equipment manufacturer 0.095 in. (2.41 mm) replacement line. Line other than the specified may make the
engine overheat or fail.
There are two methods to replace the trimming line:
• Wind the inner reel with new line
• Install a prewound inner reel
Removing the Existing Inner Reel
1. Hold the outer spool with one hand and unscrew
the bump knob counterclockwise (Fig. 17).
Inspect the bolt inside the bump knob to make
sure it moves freely. Replace the bump knob if
damaged.
2. Remove the inner reel from the outer spool (Fig. 18).
3. Remove spring from the inner reel (Fig. 18).
4. Use a clean cloth to clean the the inner reel,
spring, shaft, and inner surface of the outer spool.
5. Check the indexing teeth on the inner reel and
outer spool for wear (Fig. 19). If necessary,
remove burrs or replace the reel and spool.
NOTE: Always use the correct line length when
installing trimming line on the unit. The
line may not release properly if the line
is too long.
Single Line Installation
Go To Step 8 for SplitLine® Installation:
6. Take approximately 20 feet (6 m) of new
trimming line, loop it into two equal lengths.
Insert each end of the line through one of the
two holes in the inner reel (Fig. 20). Pull the line
through the inner reel so that the loop is as
small as possible.
7. Wind the lines in tight even layers onto the reel
(Fig. 21). Wind the line in the direction indicated
on the inner reel. Place an index finger between
the two lines to stop the lines from overlapping.
Do not overlap the ends of the line. Proceed to
step 12.
SplitLine® Installation
8. Take approximately 10 feet (3 m) of new
trimming line. Insert one end of the line through
one of the two holes in the inner reel (Fig. 22). Pull the line through the inner reel until only about 4 inches is left out.
9. Insert the end of the line into the open hole in the inner reel and pull the line tight to make the loop as small as
possible (Fig. 22).
10. Before winding, split the line back about 6 inches.
11. Wind the line in tight even layers in the direction indicated on the inner reel.
NOTE: Failure to wind the line in the direction indicated will cause the cutting head to operate incorrectly.
12. Insert the ends of the line into the two holding slots (Fig. 23).
13. Insert or slide the ends of the line through or into the eyelets in the outer spool and place inner reel with spring
inside the outer spool (Fig. 24). Push the inner reel and outer spool together.
NOTE: The spring must be assembled on the inner reel before reassembling the cutting head.
14. While holding the inner reel and outer spool, grasp the ends and pull firmly to release the line from the holding slots in the spool.
15. Hold the inner reel in place and install the bump knob by turning clockwise. Tighten securely.
INSTALLING A PREWOUND REEL
1. Hold the outer spool with one hand and unscrew the bump knob counterclockwise (Fig. 17). Inspect the bolt inside
the bump knob to make sure it moves freely. Replace the bump knob if damaged.
2. Remove the old inner reel from the outer spool (Fig. 18).
3. Remove the spring from the old inner reel (Fig. 18).
4. Place the spring in the new inner reel.
NOTE: The spring must be assembled on the inner reel before reassembling the cutting head.
5. Insert or slide the ends of the line through or into the eyelets in the outer spool (Fig. 24).
6. Place the new inner reel inside the outer spool. Push the inner reel and outer spool together. While holding the inner
reel and outer spool, grasp the ends and pull firmly to release the line from the holding slots in the spool.
7. Hold the inner reel in place and install the bump knob by turning clockwise. Tighten securely.
INSTALLATION OF THE SPEEDLOCK™
Removing the Existing Inner Reel
Refer to Removing the Existing Inner Reel in the Maintenance and Repair Insturctions section that can be found in the
operator's manual.
Installing the SpeedLock™
1. After removing the inner reel, place the SpeedLock™ onto the shaft, making sure to align the arrows with the
eyelets in the outer spool (Fig. 25).
2. Place the spring over the shaft and into the recess in the SpeedLock™ Spool (Fig. 25).
3. While holding the outer spool in place, insert the bolt located in the Bump Knob™ through the end of the spring
and into the end of the shaft (Fig. 25).
4. While slightly compessing the spring, screw the Bump Knob™ clockwise into the shaft (Fig. 25). Tighten Securely.
4
Fig. 16
Bump Knob
Bolt
Fig. 18
Fig. 17
Indexing Teeth
Fig. 19 Fig. 20
Fig. 22
Fig. 21
Index Teeth
Eyelets
Spring
Fig. 23
Fig. 24
MAINTENANCE AND REPAIR INSTRUCTIONS
Installing the Trimming Line
1. Align the arrows on the SpeedLock™ with the
eyelets on the outer spool (Fig. 26).
2. Insert a piece of precut spiral line, P/N
49UFSHLL953, into an eyelet on the outer
spool (Fig. 26).
3. Push the line into the SpeedLock™ until it
starts to show from the opposite side.
4. Adjust the line so that both ends are of equal
length (Fig. 27).
5. While holding the outer spool in place, pull the
SpeedLock™ away from the outer spool and
twist the SpeedLock™ clockwise until the dot
is inline with the eyelet or until it stops (Fig. 28).
6. Release the SpeedLock™ so that it snaps into
place.
7. Check that the SpeedLock™ has seated
completely into the outer spool. If it has not,
repeat steps 5 thru 7.
Removing the Trimming Line
1. While holding the outer spool in place, pull the SpeedLock™ away from the outer spool and twist the SpeedLock™
counterclockwise until it stops. The arrows should align with the eyelets on the outer spool. (Fig. 26)
2. Release the SpeedLock™.
NOTE: The SpeedLock™ should stand about 1/4 of an inch above the outer spool.
3. Firmly pull one end of the trimming line until the whole piece exits the outer spool.
REMOVING THE SPEEDLOCK™
1. While holding the outer spool in place, turn the Bump Knob™ counterclockwise until it completely unscrews from
the shaft.
2. Remove the spring.
3. Remove the SpeedLock™.
CHECKING THE OIL LEVEL
WARNING:
To prevent extensive engine wear and damage to the unit, always maintain the proper oil
level in the crankcase. Never operate the unit with a low oil level.
The importance of checking and maintaining the proper oil level in the crankcase cannot be overemphasized. Check oil
before each use:
1. Stop the engine and allow oil to drain into the
crankcase.
2. Place the unit on a flat, level surface to get a
proper oil level reading (Fig. 32).
3. Keep dirt, grass clippings and other debris out
of the engine. Clean the area around the
dipstick before removing it.
SEE
4. Remove the oil fill plug/dipstick and wipe off oil.
p. 4
Reinsert it all the way back in. (Fig. 30)
5. Remove the oil fill plug/ dipstick and check the oil level. Oil should be up to the top of the dipstick (Fig. 29).
p. 4
6. If the level is low, add a small amount of oil to the oil fill hole and recheck (Fig. 30). Repeat this procedure until the
p. 4
oil level reaches the top of the dipstick.
p. 5
NOTE: Do not overfill the unit.
p. 5
NOTE: Make sure the O-ring is in place on the oil fill plug/ dipstick when checking and changing the oil (Fig. 29).
p. 5
CHANGING THE OIL
CAUTION:
Wear gloves to prevent injury when handling the unit.
For a new engine, change the oil after the first 10 hours of operation. Change the oil while the engine is still warm. The
oil will flow freely and carry away more impurities.
1. Unplug spark plug boot to prevent accidental
starting.
2. Remove the oil fill plug/dipstick.
Outer Spool
3. Pour the oil out of the oil fill hole and into a
container by tipping the unit to a vertical
position (Fig. 31). Allow ample time for
complete drainage.
Spring
4. Wipe up any oil residue on the unit and clean
Inner Reel
up any oil that may have spilled. Dispose of the
oil according to Federal, State and local regulations.
5. Refill the crankcase with 3.04 fl.oz. (90 ml) of SAE 30 SF, SG, SH oil.
NOTE: Use the bottle and spout saved from initial use to measure the correct
amount of oil. The top of the label on the bottle measures approximately
3.04 ounces (90 ml) (Fig. 33). Check the level with the dipstick. If the level
is low, add a small amount of oil and recheck. Do not overfill (Fig. 32).
6. Replace the oil fill plug/dipstick.
7. Reconnect the spark plug boot.
AIR FILTER MAINTENANCE
Loop
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
Clean and re-oil the air filter every 10 hours of operation. It is an important item to
maintain. 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. 34).
Loop
NOTE: It may be necessary to remove the fuel cap to completely remove the air filter
cover.
2. Remove the air filter (Fig. 34).
3. Wash the filter in detergent and water (Fig. 35). Rinse the filter thoroughly and
allow it to dry.
4. Apply enough clean SAE 30 motor oil to lightly coat the filter (Fig. 36).
5. Squeeze the filter to spread and remove excess oil (Fig. 37).
6. Replace the filter (Fig. 34).
NOTE: If the unit is operated without the air filter 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. 34).
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. 34).
9. Replace the fuel cap if you have removed it.
CARBURETOR 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. 338).
NOTE: Careless adjustments can seriously damage your unit. An authorized service dealer should make carburetor
adjustments.
Check Fuel
Old fuel is usually the reason for improper unit performance. Drain and refill the tank with fresh 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. 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
WARNING:
The cutting attachment may spin during idle speed adjustments. Wear protective clothing
and observe all safety instructions to prevent serious personal injury.
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. 38). 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
Outer Spool
SpeedLock™
Shaft
Spring
Bump Trimmer
Eyelet Recess
Knob™ Line
Fig. 25 Fig. 26
Even
Trimmer
Line
Cutting Head
Fig. 27 Fig. 28
Oil Fill Plug/ Dipstick
Oil Fill
Plug
O-Ring
Full
Add 1.4-
1.5 oz.
O-Ring
(41-44 ml)
Oil Fill
Hole
Fig. 29
Fig. 31 Fig. 32
Fill Line
Air Filter
Fig. 35
Fig. 36 Fig. 37
Idle Adjustment Screw
Arrow
Eyelet
SpeedLock™
Dot
Eyelet
Fig. 30
Fig. 33
Air Filter Cover
Tab
Fig. 34
Fig. 38