Classic Cycles Technical Resources
59
The ignition coil induces high voltage current supplied by the battery by the operation of the contact
breakers. The amount of high voltage current induced is determined by the ratio between the number of
windings on the primary coil and secondary coil. This high voltage current is supplied .to the spark plugs.
The Bridgestone 175 DT has a battery ignition system. Twelve volt battery current flows into the primary
coil of the ignition coil. When this primary current is cut off suddenly by the operation of the contact
breaker, high voltage current is induced in the secondary coil.
C. Technical Standards:
The technical standards of electrical components are indicated below:
DESCRIPTION SPECIFICATIONS 175DT
Condenser Capacity in Microfarads — 0.25 to 0.30 mfd X
Ignition Coil
(Primary)
Operating Voltage — 12.0 volt X
Operating Amperage — 1.5 amps (each) X
Ignition Coil Primary Continuity
Right Coil (White wire to blue wire) —
4.5 to 5.0 ohms
X
Left Coil (White wire to blue wire) —
4.5 to 5.0 ohms
X
Secondary Continuity
Right Coil (Blue wire to high tension) —
9000 to 10,000 ohms
X
Left Coil (Blue wire to high tension) —
9000 to 10,000 ohms
X
NOTE: Refer to Troubleshooting section for proper testing procedures in checking generator and charging
system on B/S 175 DT.
D. Generator:
The generator fitted to the BS 175 DT is a six pole, magnetic, inner
rotor type AC dynamo. The dynamo consists of a rotor into which
magnets are cast and a stator consisting of an iron core and wires
wound around the iron core. The timing gear is fitted on one end of
the rotor and a cam which operates the contact breakers is fitted
on the other end. A six pole permanent magnet is contained in the
center of the rotor.
To increase output, anisotripic cast magnets, which are specially
treated for magnetizing, are used. The principle of the generator is
the same as that of a conventional magneto, but the stator consists
of three coils as shown in Fig. 119, so the dynamo generates three
phase alternating current.
Outstanding features of the magneto type AC dynamo are good resistance
to vibration, capability for high speed operation, etc. This type of dynamo is
particularly suitable for high speed motorcycles.
All Bridgestone 175 models after serial No. 16G 11761 are equipped with
an improved type generator. This new style generator is driven by an extra
gear and is turning at crankshaft speed rather than ½ crankshaft speed as
did the older type. NOTE: Timing procedure is the same as old style except
points for right cylinder are located at the top and points for left cylinder
are located at the bottom of the generator.
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