Troy-Bilt TB525CS - Manual (Page 13)

13
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. 43).
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.
43).
5. 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. 44). Remove the rocker arm
cover and gasket.
6. Pull the starter rope slowly to bring
the piston to the top of its 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. 45).
• Both rocker arms move freely, and both valves are closed.
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. 42).
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
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. 42). 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.
MAINTENANCE AND REPAIR INSTRUCTIONS
WARNING: 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.
Idle Adjustment Screw
Fig. 42
Remove
Screws
Fig. 43
View Of The Rear Engine Cover
Rocker
Arm
Cover
Fig. 44
Spark
Plug
Hole
Air Filter Cover
Air Filter
Tab
Fig. 41
Remove
Screws
Adjusting Nuts
Feeler Gauge
Rocker Arms
Fig. 45
INTAKE
EXHAUST
Spark Plug
Hole