Section G2C - Royal Enfield SPRING FRAME O.H.V. 250cc CLIPPER 1954 Workshop Maintenance Manual

ROYAL ENFIELD WORKSHOP MANUAL
Miller A.C. Generator and Rectifier
Used on " 250 Clipper," 1954 and early 1955
1. General Description
The lighting and ignition set consists of a
battery and coil ignition system plus a means of
charging the battery from a permanent magnet
A.C. generator (Fig. 1) through a full wave
selenium rectifier (Fig. 2) which acts in effect
like a pair of non-return valves converting the
A.C. current into uni-directional current which is
used to charge the battery. Current is drawn
from the battery to light the lamps and energise
the ignition coil but an "emergency start"
position is provided on the switch (Fig. 3) to
enable the engine to be started with a flat
battery, or even with no battery at all.
The generator consists of a rotor mounted on
the end of the driving shaft of the engine and

SECTION G2c

Lighting and Ignition Set
containing six powerful permanent magnets of
"Alcomax" arranged to produce six poles,
alternatively north and south.
Surrounding the rotor is the stator consisting
of six coils carried on a laminated core plate. On
earlier models the stator was mounted in the
outer half of the chaincase which was accurately
located relative to the rotor by means of a centre
bearing. On later models the stator is mounted
on the inner half of the chaincase which itself is
accurately located on the engine crankcase. This
method of mounting has the advantage that the
clearance between rotor and stator poles can
readily be checked with feelers after removal of
the chaincase outer half. The nominal air gap is
.015 in. If the gap is less than .008 in. at any
point there is a risk of fouling when the engine
is running under load.
The headlamp (see Section G5b) is mounted
in a specially designed "Casquette" fork head
which contains an ammeter with warning light
and a six position lighting and ignition switch.
2. Switch Positions
2 (a). Parking
Pilot light, speedometer light and tail light
are connected to the battery. There is no
connection to the ignition coil and the engine
can NOT be started nor run with the switch in
this position.
Section G2c Page 1