MTD LT31CSH Brush Cutter User Manual


 
19
MAINTENANCE AND REPAIR INSTRUCTIONS
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 or flat blade
screwdriver into the hole in the air filter/muffler 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.
Fig. 38
Idle Speed Screw
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.
REPLACING THE SPARK PLUG
Use a Champion RDJ7Y spark plug, or equivalent. The
correct air gap is 0.020 inch (0.5 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-inch socket
counterclockwise.
3. Replace a cracked, fouled or dirty spark plug. Set
the air gap at 0.020 in. (0.5 mm) using a feeler gauge
(Fig. 39).
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.
0.020 in.
(0.5 mm)
Fig. 39
The cutting
attachment may spin
during idle speed adjustments. Wear
protective clothing and observe all safety
instructions to prevent serious personal injury.
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.
WARNING:
Checking the fuel mixture, cleaning the air filter, and
adjusting the idle speed should solve most engine
problems. If not and:
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.