your right , thats a lousy discription .
if its a lone wire snaking down and under the engine ... its the oil pressure switch wire .
but i think it should come down the front down tube ?
the only other wires into the engine are the 2 points wires
... a wire comes from each coil ... one white/black .... one white/yellow
each wire runs a set of points . they enter at the back top of transmission .
it could also be ... un-used wires , prewired but unused ... to run turn signals ?
one green/w red
one green/w white .