Troy-Bilt TB144 Operator's Manual page 13

2. Remove the screw behind the engine cover (Fig. 24).
Screw
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
RockerArm
Fig. 24
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.
Rocker Arm Cover
Spark Plug Hole
Gasket
Fig. 25
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, and both valves are closed
If these statements are not true, repeat this step.
Rocker Arms
INTAKE
Adjusting Nuts
0.003-0.006 in.
(0.076-0.152 mm)
Intake Valve Feeler Gauge
Stem
D_gagement
d'admission:
.076-0.152 mm Exhaust Valve
(.003-.006 in.) Stem
Fig. 27
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.
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.
EXHAUST
Feeler Gauge
Fig. 26
13