Troy-Bilt TB144 Manual Del Operador página 16

MAINTENANCE AND REPAIR INSTRUCTIONS
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. 27)
• Both rocker arms move freely, and both valves are
closed
If these statements are not true, repeat this step.
8. Slide the feeler gauge between the rocker arm and
the valve return spring. Measure the clearance
between the valve stem and rocker arm (Fig. 29).
Measure both the intake and exhaust valves.
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 28 and 29.
Rocker Arms
INTAKE
Feeler Gauge
16
Adjusting Nuts
EXHAUST
Fig. 28
Adjusting Nut
0.003–0.006 in.
(0.076–0.152 mm)
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. 29).
• To increase clearance, turn the adjusting nut
counterclockwise.
• To decrease clearance, turn the adjusting nut
clockwise.
b. Recheck both clearances, and adjust as necessary.
10. Reinstall the rocker arm cover using a new gasket.
Torque the screw to 20–30 in
11. Reinstall the engine cover. Check alignment of the
cover before tightening the screws. Tighten screws.
12. Check the spark plug and reinstall. See Replacing
the Spark Plug.
13. Replace the spark plug wire.
Rocker Arm
Feeler Gauge
Valve Stem
Fig. 29
lb (2.2–3.4 N m).
• •