Chapter 1: INTRODUCTION
8
9. Intake valve lash (carburetor side) should be
.003”-.005” (.10
+ .02mm). See Figure 1.10.
10. Exhaust valve lash (muffler side) should be .005-
.007” (.15
+ .02mm). See Figure 1.11.
11. Use a 10mm wrench to loosen the jam nut, and
a 14mm wrench to adjust the rocker arm fulcrum
nut.
See Figure 1.11.
• Tighten the rocker arm fulcrum nut to close-up
the clearance between the end of the valve stem
and the contact point on the rocker arm.
• Loosen the rocker arm fulcrum nut to open-up
the clearance between the end of the valve stem
and the contact point on the rocker arm.
12. Hold the fulcrum nut with a 14mm wrench,
tighten the jam nut to a torque of 79.7 - 106.2 in-
lb. (9-12 Nm) using a 10mm wrench.
13. Double-check the clearance after tightening the
jam nut, to confirm that it did not shift. Re-adjust
if necessary.
14. Rotate the engine through several compression
cycles:
• Observe the movement of the valve gear.
• Return the piston to TDC compression stroke
and re-check the valve lash to confirm consistent
movement of the valve gear, including the slight
bump to the exhaust valve from the automatic
compression release.
15. Clean-up any oil around the valve cover open-
ing, clean the valve cover, replace the valve
cover gasket if necessary.
16. Install the valve cover, tightening the valve cover
screws to a torque of 62 - 80 in-lbs (7-9 Nm).
IMPORTANT: Over tightening the valve cover
will cause it to leak.
17. Install the spark plug.
Spark arrestor
The spark arrestor should be checked and/or cleaned
every 25 hours. Clean spark arrestors by following the
steps described in Chapter 8: Exhaust.
NOTE: The spark arrestor also helps to keep
potential blockages out of the exhaust system.
Typical blockages include insect nests built dur
-
ing the dormant season.
Cleaning the engine
1. To maintain a proper operating temperature and
to keep the equipment looking good all debris
should be removed from the engine.
2. It is recommended to use compressed air to
blow all of the debris off of the engine.
NOTE: A pressure washer may be used to clean
outdoor power equipment but only after the unit
has been allowed to properly cool.
NOTE: Debris can build up under the deck and
cause the engine to operate under an unin
-
tended load.
Figure 1.10
.004” feeler
gauge
Figure 1.11
.006” feeler
gauge
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