Magneto Maintenance
Adjustment
of
Contact Breaker Setting.
The setting of the contact breaker
must be checked every 3,000 miles (5,000 kms.). To do this, remove the contact
breaker cover and turn the engine until the contacts are seen to be fully open.
Check the gap with afeeler gauge having a thickness of 0.012"-0.015" (0.30 to 0.40 rnm.).
a gauge for this purpose is provided on the spanner usually supplied with each
magneto. If the setting
is
correct, the gauge should be a sliding
fit,
but if the gap
width varies appreciably from the gauge thickness
it
must be adjusted. Keep the
engine in the position giving maximum separation of the contacts,~lacken the locknut
and turn the contact screw by
its
hexagon head until the gap
is
set to the gauge.
Tighten the locknut and re-check the setting.
Cleaning Contacts. .Every 6,000 miles (10,030 kms.), take off the contact breaker
cover and examine the contact breaker. Dirty or pitted contacts can ,be cleaned
with a tine carborundum stone, or, if this
is
not available, very fine emery sloth can
be used.
Wipe away any dirt or metal dust with
a
cloth moistened with petrol. Contact
breaker springs should be examined and any rust removed. To render the contacts
accessible for cleaning, proceed as outlined below.
After cleaning, check the contact breaker setting.
Removal of Contacts for Cleaning. Unscrew the contact breaker securing screw.
Carefully lever the contact breaker
off
the tapered shaft on which
it
fits.
Push
aside the locating spring and lift the rocker arm OH
its
pivot, when
it
will be possible
to clean the contacts. When replacing the contact breaker, check that the pro-
jecting key, on the tapered portion of the contact breaker base, engages with the
keyway cut in the armature spindle, otherwise the timing of the magneto will be
affected. Replace the contact breaker securing screw and tighten with care.
High Tension Pick-up.
About every 6,000 miles (10,000
kms.), remove the high
tension pick-up.
Wipe the moulding with a clean dry cloth.
Check that the
carbon brush moves freely in
its
holder. but take care not
to
stretch the brush spring
unduly.
If the brush
is
dirty, clean
it
with a cloth moistened with petrol. If the
brush
is
worn to within
+"
(3.0 mm.) of the shoulder
it
must be renewed.
Before re-fitting the high tension pick-up, clean the slip ring track and'flanges by
pressing a soft dry cloth on the ring with a suitably shaped piece of wood, while the
engine
is
slowly turned.
Renewing High Tension Cables. When high tension cables show signs of-cracking
or perishing, they must be replaced, using
7
mm. rubber covered ignition cable.
To replace a high tension cable proceed
as
follows:-
Remove the metal washer and moulded terminal from the defective cable. Thread
the new cable through the moulded terminal and cut back the insulation
for
about
F
(6.0 mm.). Pass the exposed strands through the metal washer and bend them
back radially. Screw the terminal into the pick-up moulding.
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