Troy-Bilt TB144 Operator's Manual page 16

3. Disconnect the spark plug wire.
4. Clean dirt from around the spark plug. Remove the
spark plug from the cylinder head by turning a 5/8 in.
socket counterclockwise.
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. 26). Remove the rocker arm cover and gasket.
Rocker Arm Cover
Spark Plug Hole
Fig. 26
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. 26).
Both rocker arms move freely, 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. 27 & 28).
Measure both the intake and exhaust valves.
The recommended clearance for the intake is .003 - .006
in. (.076 - 0.152 mm). The recommended clearance for
the exhaust is .013 - .016 in. (.330 - 0.406 mm).
Use a standard automotive feeler gauge at .005 and .015 in.
(0.127 and 0.381 mm). The feeler gauge should slide
between the rocker arm and valve stem with a slight amount
of resistance, without binding. Figure 27 shows how to
measure the intake clearance, while Figure 28 shows the
exhaust clearance.
Rocker Arms
INTAKE
Adjusting Nuts
EXHAUST
Feeler Gauge
Exhaust
A_usting Nut_
Exhaust
Clearance:
.013-.016in.
(.330-0.406mm)
@
Fig. 27
Exhaust
Rocker Arm
Stem
Intake Clearance:
.003-.006 in. \
(.076-0.152 mm) Exhaust Valve Stem
Fig. 28
9. If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 ram)
wrench or nut driver (Fig. 28).
• 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.lb (2.2-3.4 N.m).
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.
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