8. Install the push rods, rocker arms and rocker arm
nuts.
9. Set the valve clearance. See Figure 39.
10.
Install and adjust the decompression mechanism.
11.
Install the rocker cover. Remove the
solenoid,
dip
plunger "O" ring in oil and reinstall when cover is
on engine.
After the first
SO
hours of operation, retighten the cylinder head
bolts and check valve clearance.
INTERNAL
DISASSEMBLY
If engine disassembly is necessary, observe the
following order
(i.e.,
flywheel, gear cover . . .). As
disassembly progresses, the order may be changed
somewhat as will be self-evident. The engine
assembly procedure is the reverse of disassembly.
Any special assembly instructions for a particular
group are included in the applicable section. When
reassembling, check each section for these special
assembly instructions or procedures.
FLYWHEEL
Remove the blower
housing.
The flywheel is
a
tapered
fit on the crankshaft. Improvise a puller using at least
a 7/16-inch bar and drilling two 7/16-inch holes 2-7/8-
inches between centers. Loosen theflywheel moun-
ting screw a few turns. Place bar against the flywheel
screw, attach bar using two 3/8-16 thread screws in
the holes provided in flywheel. Alternately tighten the
screws until flywheel is free.
Replacement flywheels are supplied without the
timing markings because each flywheel must be fitted
to its engine. The only accurate method of deter-
mining the top dead center (TDC) and port closing
points is to measure the piston travel. This is a critical
measurement and should be attempted only with
accurate, dependable equipment.
With the flywheel mounted, remove the head and
install a depth gauge over the front piston. Rotate the
flywheel to find the TDC position on the compression
stroke and mark this point on the flywheel. Next, turn
the flywheel counterclockwise until the piston drops
exactly 0.102 inch from TDC. This is the port closing
point, 17° BTDC. Mark it on the flywheel.
Ring
Gear
To remove the ring gear (if damaged), saw part way
through,
then break it using a cold chisel and heavy
hammer.
To install a new ring gear, place it in an oven heated to
380-400° F for 30 to 40 minutes. '
When heated properly, the ring will fall into place on
the flywheel. If it does not go on all the way by itself,
drive it into place with a hammer. Do it fast and do not
damage the gear teeth. The ring will contract rapidly
and may shrink to the flywheel before it is in place. If
this occurs, a new ring gear may be required.
GEAR
COVER
To remove the gear cover, detach the upper governor
ball joint. Removethe governor speed adjustment nut
and governor spring bracket.
Remove the screws holding the gear cover to the
crankcase. To loosen the gear cover, tap it with a soft
hammer.
Governor
Shaft
The governor shaft is supported by two sets of needle
bearings. To remove the shaft, remove the yoke and
pull the shaft from the gear cover. If the shaft is
binding,
clean the bearings; if loose, replace the
bearings. To remove the larger bearing, drive both
bearing and oil seal out from the outside of the gear
cover. Remove the smaller bearing with an Easy-Out
or similar
tool.
Press new bearings and oil seal into
place.
Gear
Cover
Oil
Seal
Replace the oil seal if damaged or worn. Drive the oil
seal out from insidethegearcover. See Figure44. Lay
the cover on a board so the seal boss is supported.
Using an oil seal driver, insert the new seal from the
inside with rubber lip toward outside of gear cover
(open side of seal inward) and drive it flush with the
outside surface. During gear cover installation, use
the driver to protect the oil
seal.
•-GEAR COVER
INSTALL OIL SEAL
FLUSH WITH THIS
SURFACE
OIL SEAL
[ CAUTION j
Do not heat with
a
torch.
Damage to
ring
gear
will result.
THIS SURFACE MUST
BE CLEAN BEFORE
INSTALLING SEAL
FIGURE 44. GEAR COVER OIL SEAL
39
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