Section G1E - Royal Enfield 350 BULLET 1956 Workshop Maintenance Manual

ROYAL ENFIELD WORKSHOP MANUAL
Lucas Rotating Magnet Magneto Model SR1
Used on 350 Bullet 1956-59; 500 Bullet 1956-59
1. General
The magneto rotor comprises a permanent
magnet fitted with two laminated pole shoes. The
stator consists of laminated pole pieces bridged by
a laminated coil core. The coil has concentrically
wound primary and secondary windings.
The rotor is driven by the engine through an
automatic advance coupling and induces an
alternating magnetic field in the laminated iron
core of the coil. This field in turn induces
alternating voltages in the primary and secondary
windings of the coil. Magnetic flux due to current
flowing in the primary winding tends to oppose
any change in direction of the magnetic field in the
laminated iron core. In this way, field reversals due
to the rotating magnet are delayed until the
contact breaker opens. This removes the
restraining influence of the primary winding and
the consequent rapid reversal of the magnetic flux
linked with the coil causes a high voltage to be
induced in the secondary winding.
The body of the magneto is formed of a single
casting enclosed at the contact breaker end by a
moulded cover. The cover is designed with the
high tension cable outlet in a downward direction,
SECTION G I e
thus preventing the retention of moisture at the
terminal connection. The coil and capacitor are
robustly constructed and specially treated to
withstand very arduous condition.
2. Routine Maintenance
(a) Lubrication:
TAKE GREAT CARE TO PREVENT
OIL OR GREASE GETTING ON OR
NEAR THE CONTACTS.
(i) After 1,000 running hours (say 30,000 mile.)
remove the moulded cover, slacken the nut
securing the end of the contact breaker spring and
lift off the moving contact assembly. Smear the
pivot pin with a small quantity of Mobilgrease No.
2 or its equivalent.
(ii) The magneto rotor is mounted on ball
bearings. These bearings are packed with high
melting point grease before leaving the factory
and require no attention for a considerable time.
About every two years, or when the engine is
undergoing a general overhaul, the magneto
should be dismantled by a Lucas Service Depot or
Agent and the bearing repacked with high melting
point grease.
Section G1e Page 1