Re: power to the coil

["James J Schneider" <jjschneider@xxxxxxxxxxxx>]

"I put the newer
motor on the old bike frame.  ... All I had to do was put the
rotor/stator from my old engine on it ."


Barry,

The coils don't care which side they are on, but the plug wire lengths are
probably different, dictating their position, and you must make sure to get
the low voltage wires hooked up to the correct coils, on the correct
terminals.  The coils from the different years should be interchangable.
Yes, the safety relays will cut off your spark.  And testing coils is
pretty easy - test resistance between the two low voltage terminals, and
also between one of them and the plug cap.

Coils get power through one of the low voltage terminals, the one hooked up
to the + side of the coil.  They have a constant 12V when the engine is
running.  They are switched on the negative side; the ground connection is
made and broken at the proper times by the TCI, which acts under guidance
from the reluctor and pickup.  The reluctor is a magnetic thing on the
rotor; the pickup is mounted to the LH case cover and detects the reluctor
going by, sending a signal to the TCI when it does.  This is how the TCI
knows where the crank is, angle-wise, so that it can properly time the
spark.  Which brings me to what I think your problem is.  What year is the
parts engine. what year is your bike, and what case cover and pickup did
you use?  You said you used the rotor and stator from the old engine.  Did
you also use the case cover and pickup from the old engine?  If so, you did
the right thing and your problem is elsewhere, but if not this could very
well be your problem as Yamaha changed the pickup and reluctor design, more
than once I think.

Jeremy
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