[Seeker]

the 3 yellow wires you mentioned are part of the alternator (the stator) and are used for generating the ac voltage which goes to the rectifier/regulator to charge the battery. There's another coil that picks up the crankshaft rotation which is equivalent to the contact breakers on old bikes (if you're old enough to remember those). It produces a pulse (or several pulses) as the crankshaft rotates and tells the ECU to fire the plugs at the right time, if it doesn't produce a pulse you won't get a spark.