Villiers MARK 12D, Operating Instructions And Spare Parts List

Page: 8 / 53

.• i.
•
changing
down from top to
middle, and middle
to bottom gear, LIFf
the lever
against its stop for each position. The lever is adjustable for
position to suit the individual ri,der, and by releasing the clamp bolt, can
be removed from the splined spindle and refitted in an alternative position.
Certain specifications of engines have a " direct " change mechanism
where the gear lever has a definite position for each gear.
CLUTCH.
The drive from the engine to clutch is taken by a pre-stretched endless
roller chain running in the oil bath chaincase. No attention is necessary
beyond that of lubrication, and correct adjustment of push rod to give
the necessary clearance to prevent clutch slip.
Whilst the clutch is
engaged, i.e. driving, there must be clearance between end of pushrod
and the clutch lever fitted to gearbox, and a special adjuster having
a
. knurled and slotted head is provided so that adjustment can be made by
hand without having to use tools. There should be about -h- inch free
movement at the end of gearbox clutch lever before commencing to
depress the clutch springs. When new corks are fitted they must be
ground to a thickness of for the chainwheel and 1\'' for the tanged
plate, after fitting to the plates.
MAGNETO.
The magneto fitted to both engines is the latest 6-pole pattern providing
current for ignition and lighting,-the same magneto being used for both
the "DIRECT" and "RECTIFIER" lighting sets available with each
type of engine. The wiring connections differ, however, and reference
should be made to the wiring diagrams Figs.
12
and
13.
The Flywheel
should not be removed unless absolutely necessary, and then it is advis­
able to use a Villiers "Hammer-tight" spanner on the centre nut which
is exposed after removal of flywheel cover. The centre nut is imprisoned
in the flywheel and acts as an extractor when turned anti-clockwise.
The armature plate which carries the ignition coil, lighting coils and
contact breaker mechanism is secured to the engine crankcase by six
screws. The H.T. Lead from ignition coil to sparking plug is detachable
by unscrewing from armature plate, and when refitting it is important to
make sure that the
brass pad carried by the spring and secured to the
terminal, makes contact with the soldered disc on the outside of the
ignition coil. The high output magneto wiring diagram is not shown, and
reference must be made to the machine manufacturer's handbook for this
information.
Timi.ng
of the
Magneto.
The contact breaker points must commence to open before
the piston reaches the top of its stroke. In the case of the
Mark 12D and Mark 8E Engines this dimension it inch.
Timing marks are provided on the armature plate and
flywheel
rim.
In the armature plate a slot is cut in line with the
H.T. terminal, and the mark stamped on flywheel rim coincides
with the slot when the piston is at TOP of stroke, the necessary
amount of advance having been allowed. When timing ignition,
necessary because of the flywheel removal, loosely fit flywheel to
shaft, and, having set piston at correct distance BEFORE top dead
centre,
rotate flywh
e
el without turning the crankshaft until the