Royal Enfield CONSTELLATION 1958, Workshop Maintenance Manual

Page: 73 / 106

CIRCUIT DIAGRAMS FOR POSITIONS OF
LIGHTING SWITCH
Fig. 3
In the "Pilot" position these coils are
disconnected and the regulating fluxes are
consequently reduced. The alternator output
therefore increases and compensates for the
additional parking light load.
In the “Head” position the alternator output is
further increased by connecting all three pairs of
coils in parallel.
4. Emergency Starting
An emergency starting position is provided
on the ignition switch. This is for use if the
battery has become discharged and a normal start
cannot be made. In the switch position "EMG"
four coils of the alternator are connected through
one arm of the rectifier to the primary winding of
the ignition coil, with the contact breaker in
series.
This system, which on a single cylinder
machine could cause trouble through unwanted
sparks on the compression stroke of the engine,
does not do so on the twin, owing to the fact that
the distributor permits the passage of a spark
only when the engine is near the firing position.
To ensure easy starting in the "EMG" position
of the switch, the stator and rotor poles of the
A.C. generator must be correctly positioned. This
is ensured by: (a) fitting the rotor sleeve so that
the keyway is at the top when the engine is at
T.D.C.; (b) seeing that the key is correctly fitted;
(c) fitting the stator so that the leads enter it at
the top, at the back of the stator, and (d) timing
the contact breaker correctly, i.e., so that the
points are just about open when the pistons are
1/32 in. before T.D.C.
After starting on the "EMG" position, the
switch should be returned to the "IGN" position.
EMERGENCY STARTING CIRCUIT
Fig. 4
5. Direct Operation
Short journeys without the battery can be
made with the switch in the "EMG" position. To
do this, the cable normally connected to the
battery negative terminal must be connected to
an earthed point on the machine. If lights are
required when the battery is disconnected, use
only the headlights and keep the engine speed
low to prevent excessive voltage rise.
6. Routine Maintenance
The alternator and rectifier require no
maintenance apart from ensuring that all
connections are clean and tight.
If the rotor, stator, engine crankshaft or rear
half of the chaincase have been disturbed, the air
gap between the rotor and stator should be
checked. If a feeler gauge of at least .008 in.
thick cannot be passed between the rotor and
each of the stator poles the alignment should be
checked.
The nuts which clamp together the rectifier
plate assembly must not under any
circumstances be slackened. They have been
carefully set during manufacture to give correct
rectifier performance. A separate nut is used to
secure the rectifier to the frame of the
motorcycle.
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