Carburetor Adjustment; Spark Arrestor Maintenance - MTD Yard Machines Y780 Manual Del Operador

4. Apply enough clean SAE 30 oil to lightly coat the filter (Fig. 35).
5. Squeeze the filter to spread and remove excess oil (Fig. 36).
Fig. 35
6. Replace the air filter inside the air filter/muffler cover (Fig. 33).
NOTE: Operating the unit without the air filter and air filter/
muffler cover assembly will VOID the warranty.
Reinstalling the Air Filter/Muffler Cover
1. Place the air filter/muffler cover over the back of the
carburetor and muffler. Align the screw holes.
2. Insert the four (4) screws into the holes in the air filter/muffler
cover (Fig. 32) and tighten. Do not over tighten.

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. 37). Remove the screw using
either a torx #20 or flat blade screwdriver.
Spark Arrestor
Hood
Screw
Spark Arrestor
Tabs
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.
MAINTENANCE AND REPAIR INSTRUCTIONS
Fig. 36
Engine
Slots
Screen Muffler
Fig. 37

CARBURETOR ADJUSTMENT

The idle speed of the engine is adjustable through the air filter/
muffler cover (Fig. 38).
NOTE: Careless adjustments can seriously damage your unit. An
authorized service dealer should make carburetor adjustments.
Check Gasoline Mixture
Old and/or improperly mixed gasoline is usually the reason for
improper unit performance. Drain and refill the tank with fresh,
properly-mixed gasoline prior to making any adjustments.
Refer to Oil and Gasoline 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/gasoline 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 gasoline 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.
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 gasoline 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.
WARNING:
during idle speed adjustments. Wear protective
clothing and observe all safety instructions to
prevent serious personal injury.
12
Idle Speed Screw
Fig. 38
The cutting attachment may spin