Date: Sun, 14 Nov 1999 08:24:52 -0500
From: Chris L Johnson 

Wiring is a very simple affair concerning trials bikes, even with lights.
 Way simple when you consider a trials bike with no lights, which is the
norm in the US.  

You have usually four wires from the engine: three that go to the coil
(like red, green, and brown), and one, a yellow wire, that is the 12V AC
for powering lights and fan.  Sometimes that power circuit branches into
two parts.  One is for the fan, and the other for the lights.  Thus you
will see two power modification components to convert AC to DC or
something in between.  Thus the fan will have a regulator, as will the
lights.  

The power circuit for the fan is simple.  You have the 12VAC from the
motor being modified to DC or half-ass DC.  Either the input to the
regulator or the output will pass through the thermal on/off switch on
the head and on to the fan.

The power circuit for the lights has its own regulator.  If you are not
running lights, that whole gaggle of stuff can come off.  You thus end up
with.

- Three wires from motor into coil.  The fourth wire (black) from the
coil is the kill switch wire that grounds the coil to kill the motor.

- The yellow 12VAC wire that branches to the fan regulator, thermal
on/off switch, and fan

Even I, a measly mechanical engineer that doesn't like the fact that I
can't see electrons, can figure it out.

Chris Johnson
Scorpa 250 EZ Fun/Gas-Gas 160/Fantic 305/Yamaha Virago 1,100/XV920RH Euro
and now vintage `74 TY 250
chris "at" college-park.com as Director of Engineering at College Park
see www.college-park.com and papazit "at" juno.com (personal address)