Rocker Arm Clearance; Carburetor Adjustment - Troy-Bilt TB525CS Operator's Manual

Air Filter Cover
Tab
Fig. 36
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. 37).
NOTE: Careless Idle Adjustment Screw
adjustments can f
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 Fig.37
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: To prevent serious personal injury,
make sure the cutting attachment has stopped
rotating before you turn it off and set it down.
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 in between the Air Filter
Cover and the Engine Cover (Fig. 48). 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.
WARNING: The cutting attachment may spin during
idle speed adjustments. Wear protective clothing and
observe all safety instructions to prevent serious
personal injury.
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.
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 every 25
hours of operation.
• 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 six (6) screws on the back of the engine cover
with a Flat-head or T-25 Torx screwdriver (Fig. 38).
2. Disconnect the spark plug wire.
3. Clean dirt from around the spark plug. Remove the spark
plug from the cylinder head by turning a 5/8 in. socket
counterclockwise.
4. Remove the engine cover (Fig. 38).
View Of The Rear Engine Cover
Remove
Screws
Fig. 38
Clean dirt from around the rocker arm cover. Remove the
screw holding the rocker arm cover with a large flat blade
screwdriver or Torx T-25 bit (Fig. 39). Remove the rocker
arm cover and gasket.
Pull the starter rope slowly to I
bring the piston to the top of its Rocker i I
travel, (known as top dead
center). Check that:
The piston is at the top of its
travel while looking in the
spark plug hole (Fig. 40)
Both rocker arms move
freely, and both valves are
Fig. 39
11