SCOOTER SERVICE SHEET
1051
Printed March 1960
250 c.c. O.H.V. TWIN CYLINDER SCOOTER
THE LUCAS MODEL M3 PRE-ENGAGED STARTING MOTOR
WITH ROLLER-CLUTCH DRIVE
Introduction and Servicing
GENERAL
Model M3 manually pre-engaged starting motor is a four-pole two-brush earth return machine with
series-connected field coils. A lever-operated drive assembly incorporating a roller-clutch is carried on a
straight-splined extension of the armature shaft* The starter switch is mounted on the yoke and when
the drive pinion is almost fully engaged with the flywheel ring, the contacts are arranged to close and
connect the motor to the battery:
The drive and armature are spring-loaded to the out-of-mesh position.
Overspeed protection is afforded by the clutch to prevent rotation of the armature by the engine.
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MAINTENANCE
Keep the supply terminal on the starter switch clean and tight. If the connection has become dirty, clean
the contacting surfaces and lightly smear them with petroleum jelly. No periodic lubrication
is
necessary, but
at a general overhaul the starter motor should be removed and given a thorough examination on the bench.
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PERFORMANCE DATA
The following figures are based on the use of two fully charge series-connected 6-volt batteries having a
capacity of 12 amp.-hr: at the 10-hour rate.
(a) Light running on 12 volts: 50
amp. at
6,500 - 7,500 r.p.m.
(b) Lock torque: 5.3 lb.-ft. with 240
amp. at
6.5 terminal, volts.
(c) Torque at 1,000 r.p.m.: 2.751b.-ft. with 170
amp. at
8.1 terminal volts.
SERVICING
Testing in Position
Switch on the headlamps, operate the starter and watch for the following symptoms.
(i) The lamp dims and the motor does not crank the engine.
Remove the sparking plugs and check that the engine is not abnormally
stiff. Check the battery by substitution.
(ii) The lamp does not dim and the motor does not crank the engine. Check the starter switch terminal connection for
tightness.
If the source of trouble cannot be readily located, remove the starting motor from the engine for examination
by disconnecting the battery, removing the fixing bolts from the drive and bracket and lifting the starting
motor free.
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