FLYWHEEL
The flywheel is a tapered fit on the crankshaft. Use a
flywheel puller (Onan tool number 420-0100) to
remove the flywheel.
Loosen the flywheel mounting screw a few turns.
Place bar against the flywheel screw and attach bar,
using two 3/8-16 thread screws in the holes provided
in flywheel. Alternately tighten the screws until fly-
wheel is free.
FLYWHEEL REPLACEMENT
Replacement flywheels are supplied without the tim-
ing markings because each flywheel must befitted to
its engine. The only accurate method of determining
the top dead center (TDC) and port closing (PC)
points is to measure the piston travel. This is a critical
measurement and should be attempted only with
accurate, dependable equipment.
.
Use the following procedure to locate the TDC and
PC marks on the flywheel:
With the flywheel mounted, remove the head and
install a depth gauge over the front piston. Rotate the
flywheel to find theTDC position on thecompression
stroke and mark this point on the flywheel. Next, turn
the flywheel counterclockwise until the piston drops
exactly 0.128 inch (3.25 mm). RDJC prior to Spec
P,
0.155
inch (3.94 mm). Mark both TDC and piston
drop to PC point 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°F
-
400°F (192" to 204°C) for
30
to
40
minutes.
Do
not heat with a torch or ring gear
may be warped.
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 uppergovernor
ball joint. Remove the
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. See Figure 52.
GOVERNOR ARM
GOVERNOR SHAFT YOKE
(Smooth side toward
cup)
'
GOVERNOR
C
BE SURE THAT
OIL
GOVERNOR
CUP
FIGURE
52.
GEAR
COVER
ASSEMBLY
52
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