Royal Enfield SPRING FRAME O.H.V. 250cc CLIPPER 1954 Workshop Maintenance Manual page 37

ROYAL ENFIELD WORKSHOP MANUAL
2 (b). Emergency Start
This position enables the engine to be started
on the kickstarter with a completely discharged
battery or even with no battery at all. The engine
should not be run for any length of time with the
switch in this position as it causes exceptionally
heavy currents to pass through the contact
breaker points and ignition coil and is also liable
to cause pre-ignition.
2 (c). Off
Battery and generator are both disconnected.
2 (d). Ignition and Charge
Two of the generator coils are connected to
the rectifier which produces direct current to
Section G2c Page 2
charge the battery. Current passes through the
coil and contact breaker to provide ignition. Rate
of charge at normal speeds is about 2 amps.,
increasing slightly if the battery is in a low state
of charge. Speed in top gear to balance ignition
load is 17 to 28 m.p.h., depending on the state of
charge of the battery.
2 (e). Head
All six generator coils are connected to the
rectifier which charges the battery and supplies
current for the head, tail and speedometer lights
and for the ignition. Charge rate is about the
same as in switch position (d).
2 (f). Pilot
Four of the generator coils are connected to
the rectifier which charges the battery and
supplies current for
speedometer lights and for the ignition. Charge
rate is rather higher than in switch position (d),
being normally about 3 amps.
3. Circuits
See Wiring Diagram. Fig. 4.
Emergency Start. The "outer" ends of four
of the generator coils are connected to the
ignition coil through switch terminals 2 and 1.
The inner ends are, as always, connected to No.
1 terminal of the rectifier. During the closed
period of the contact breaker current flows
through the primary winding of the ignition coil
by one of two paths depending on the direction
of the A.C. voltage produced in the generator
coils, which is, of course, changing from instant
to instant.
(i) If the "outer" ends of the coils are positive
current flows from them to terminals 2 and 1 of
the switch, then through the primary winding of
the ignition coil and the contact points to earth.
The return circuit is through the battery from the
earthed positive to the negative terminal
(charging the battery on its way) then through
the ammeter to switch terminal 6 and thence to
rectifier terminal 2 and through one rectifier
plate to terminal 1 and so back to the generator
coil.
(ii) If the "inner" ends of the "generator"
coils are positive current flows from them to
rectifier terminal 1, through one rectifier plate to
the rectifier positive terminal (or centre screw),
which is earthed and thence through the contact
breaker and ignition coil to terminals 1 and 2 of
the switch, and finally to outer ends of the
generator coils.
The second of these circuits is clearly the
easier one since it does include passage through
the battery against battery voltage. The alternator
the pilot, tail and