Royal Enfield G Workshop Maintenance Manual page 34

ROYAL ENFIELD 350cc and 500cc O.H.V. WORKSHOP MANUAL
(iii) Start the engine and set to run at normal
idling speed.
(iv) Connect the negative lead of a moving
coil voltmeter, calibrated 0-10 volts, to one of
the dynamo terminals and connect the positive
lead to a good earthing point on the dynamo
yoke or engine. Reverse voltmeter connections
on negative earth machines.
(v) Gradually increase the engine speed,
when the voltmeter reading should rise rapidly
and without fluctuation. Do not allow the
voltmeter reading to rise above 10 volts and do
not race the engine in an attempt to increase the
voltage. It is sufficient to run the dynamo up to
a speed of 1,000 r.p.m. If there is no reading,
check the brush gear, as described in (vi) below.
If there is a low reading of approximately 1/2
volt, the field winding may be at fault, see
Subsection 4(d). If there is a reading of
approximately 1.1/2 to 2 volts, the armature
winding may be at fault, see Subsection 4 (e).
(vi) Remove the cover band and examine the
brushes and commutator. Hold back each of the
brush springs and move the brush by pulling
gently on its flexible connector. If the
movement is sluggish, remove the brush from
its holder and ease the sides by lightly polishing
on a smooth file. Always replace brushes in
their original positions. If the brushes are worn
so that they do not bear on the commutator or if
the brush flexible is exposed on the running
face, new brushes must be fitted.
Test the brush spring tension with a spring
scale (see Fig. 2). The correct tension is 16 - 20
oz. and new springs must be fitted if the tension
is low.
If the commutator is blackened or dirty,
clean it by holding a petrol-moistened cloth
against it while the engine is turned slowly by
means of the kick start, with sparking plug(s)
removed.
Re-test the dynamo as in (v) above. If there is
still no reading on the voltmeter there is an
internal fault and the complete unit should be
replaced if a spare is available. Otherwise the
unit must be dismantled, see Subsection 4 (b) for
internal examination.
(vii) If the dynamo is in good order, restore
the original connections. Connect regulator unit
terminal "D" to dynamo terminal "D" and
regulator terminal "F" to dynamo terminal "F"
and check the regulator.
4 (b). To Dismantle
Remove the dynamo from the motor cycle.
To detach the dynamo from the Magdyno,
unscrew the hexagon headed nut from the
driving end cover and slacken the screws
securing the band clip.
Page 34
To dismantle the dynamo proceed as follows:
Bend back the tag on the washer "B" locking the
screw "A" (see Fig. 1). Remove this screw,
withdraw the gear "C" from the shaft with the
aid of an extractor and remove the key(s) "D"
from the shaft.
(ii) Remove the cover band "H," hold back
the brush springs and lift the brushes from their
holders.
(iii) Take out the screw "J" with spring
washer from the centre of the black moulded end
cap "G." Draw the cap away from the end
bracket, take off terminal nut "F" and spring
washer, and lift the connections off the
terminals.
(iv) Unscrew and remove from the drive end
bracket the two through bolts "L"securing the
drive end bracket "N" and commutator end
bracket "Q" to the yoke "M." Hold the nuts "K"