19
WORKSHOP MANUAL
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Also after unlocking and driving wheel inside the
case. Mounting of all bearing is realised to heated
case (100-120°C). Put the bearings into the pre-
heated halfs of engine case, getting them inline
with the machined surface intended for the crank
mechanism flywheel. Push the mainshaft and gear
–plus-hub bearing as far as the depth of locking,
wich have to be already in its place. Sealing rings
are mounted in after jointing of case halves.
Lock the mounted mainshaft bearing against
shifting with shims and drift the bolts with centre
punch.
2.6.1.
Exchange of sealing rings
The seal rings alone can be replaced while engine is in the frame. However the
primary gear must be dismounted before. Also alternator and chain gear (1.9). Remove the
lock pin and take off the damaged seal ring. Then check the true joint of the spring, oil the
seal rings and drive the latter in place with the S-72 and S-92 jigs.
2.7.
Gearbox
For the correct reassembly of gearbox it is
recommended to begin with the crank mechanism
removed from the crankcase halves in order to
ensure the maximum clearance of the layshaft. To
ascertain this clearance, fit the layshaft into
ballbearing together with the 1st. speed gear and
then clamp both crankcase halves together
provisionally with several screws. Move the
layshaft forward and backward to check its axial
clearance which should be in the range from 0 –
0,6 mm. Then remove the layshaft and locate the
crank mechanism with the centre face plate (if
this plate has been removed) into the left
crankcase half heated up to 100-120°C. The
highest temperature has to be around the
crankshaft bearing. Put wooden blocks under the
front and rear part of the crankcase half and insert
the crank mechanism into as fast as possible so
that the lock pin of centre ring fits into the recess
in the crankcase. It is not permitted to drive the
mechanism into the bearing forcefully because
this would result in its „uncentering“ and also in
damaging of bearings. If the crank mechanism
becomes jammed in the baering, drive it out of
the bearing (engine dismantling), reheat the
crankcase and repeat the operation..
