Rocker Arm Clearance - Troy-Bilt TB490BC Manual Del Operador

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
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 or flat blade screwdriver
into the hole in the air filter/muffler cover (Fig. 50). 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.
WARNING: To prevent serious personal
injury, make sure the cutting attachment
has stopped rotating before you turn it off
and set it down.
Idle Adjustment Screw
Fig. 50

ROCKER ARM CLEARANCE

This requires disassembly of the engine. If you feel
unsure or unqualified to perform this, take the unit to an
authorized service center.
NOTE: Inspect the valve to rocker arm clearance with a
feeler gauge after the first 10 hours of operation
and then every 25 hours of operation thereafter.
• 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 muffler cover by pressing down on it,
separating it from the engine cover. Using a flat
blade screwdriver, disengage the middle and front
tabs and slots first. The cover will hinge off from the
rear tab (Fig. 51).
Engine Cover
Rear Slot
and Tab
Middle Tab
Middle Slot
2. Remove the two (2) screws on top of the engine cover
with a Flat-head or T-20 Torx screwdriver (Fig. 52).
Top View Of The Engine
Engine Cover
Front Tab
Front Slot
Fig. 51
Remove Screws
Muffler
Fig. 52
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