Troy-Bilt TB144 Manual Del Operador página 11

ROCKER ARM CLEARANCE
This requires disassembly of the engine. If you feel unsure or
unqualified to perform this, take the unit to a qualified service
dealer.
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 five (5) screws with a Flat-head or T-20 Torx
screwdriver (Fig. 23).
Engine Cover
2. Remove the screw behind the engine cover with a Flat-
head or T-25 Torx screwdriver (Fig. 24).
T-25 Screw
3. Disconnect the spark plug wire.
4. Clean dirt from around the spark plug. Remove the spark
plug from the cylinder head by turning it counterclockwise
with a 5/8" socket.
5. Remove the engine cover.
NOTE: To ease engine cover removal, pull the starter rope out
a little to give some slack.
6. 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. 25). Remove the rocker
arm cover and gasket.
7. 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. 25).
• Both rocker arms move freely, and both valves are closed
If these statements are not true, repeat this step.
MAINTENANCE AND REPAIR INSTRUCTIONS
T-20
Screws
Muffler
Fig. 23
Fig. 24
Rocker Arm Cover
Spark Plug Hole
Rocker Arms
INTAKE
Feeler Gauge
8. Slide the feeler gauge between the rocker arm and the
valve return spring. Measure the clearance between the
valve stem and rocker arm. Measure both the intake and
exhaust valves (Fig. 26 & 27).
Adjusting Nut
0.003–0.006 in.
(0.076–0.152 mm)
Intake Valve
Stem
The recommended clearance for both intake and exhaust is
0.003 – 0.006 in. (0.076 – 0.152 mm). Use a standard automotive
0.005 in. (0.127 mm) feeler gauge. The feeler gauge should slide
between the rocker arm and valve stem with a slight amount of
resistance, without binding. See Figure 26 and 27.
9. If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 mm) wrench or
nut driver (Fig. 27).
• To increase clearance, turn the adjusting nut
counterclockwise.
• To decrease clearance, turn the adjusting nut clockwise.
b. Recheck both clearances, and adjust as necessary.
Gasket
Fig. 25
Adjusting Nuts
EXHAUST
Fig. 26
Rocker Arm
Feeler Gauge
Exhaust Valve
Stem
Fig. 27
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