Polaris TX Starfire Owner's Manual page 56

THREE CYLINDER IGNITION
(Con't.)
side of which three screwed holes are provided to mount
a cover of recoil stater. A six pole emmit shaped cast
magnet with pole pieces of laminated steel on its surfaces
is fixed securely by rivetting between both of the alu-
minum side plates.
2.4 Construction of CDI Unit
The outer appearance of the CDI unit is shown in the
drawing; a steel case has two flanges for mounting by each
two holes with grommets. Inside is a plate with printed
circuit providing CDI circuit and an inverse revolution
preventing circuit on it. The former circuit comprises of
a charge storing condenser and semi-conductor parts such
as voltage rectifying diodes and thyristors etc. The latter
works not to supply sparks by dissolving signal voltages
when the engine operates in the inverse direction. The
parts are molded together with polyester resin in the steel
case for providing para-shock construction.
Furthermore, as this CDI unit is intended for three
cylinder engines, even if one plug of the three is off, this
can run the engine in normal condition. However, to keep
the engine running under this circumstance it will exert
vicious effect to the endurance of the ignition coi Is be-
cause the highest voltage of coils will be produced between
the coil terminals. Therefore, in order to prevent this, the
CDI unit protects the coils by all of the three coils
stopping instantaneously the supply of sparks. When the
generated voltage from such coils can not be discharged
anywhere in the consequence that one plug cap is off at
the engine speed of more than 3,000 RPM. And then,
when spark discharge is stopped and engine speed is down,
the thyristors will work again to operate normally. In the
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