Maxim "X" Mystery Wire?????

I'm working on an '85 Maxim X for a friend. I happened to notice a single black wire with a slip-on spade terminal hanging down between the #1&2 header pipes and the radiator. It's not connected to anything, and to my knowledge and the owner's, everything works I've searched but can't find anything disconnected. It's quite long; probably 18" or more. Any ideas?

 

Meter it for both Voltage and Continuity to GROUND.

There are Mousekateers that use ANY wire for 12V Power. Check it for 12V with the Switch ON and OFF and the Bike running.

If it's BLACK ... and NOT a Mickey-Moused Power wire. Wrap-up the slack and ground it.

If, as you say, ALL systems are GO. Whatever needs that Ground wire (if it's a Ground wire -- and probably IS) ... has made Ground being attached to the frame.

Don't think it can't be HOT. I've seen every imaginable COLOR and CODE used as a 12 Volt source for Powering who-knows-what!

 

It has resistance to ground......but not straight continuity. It also reads voltage.....with power on.......but not 12 volts. (it gave a tiny spark when grounded but did not blow any fuses). I've clipped the spade terminal and tied up the wire....told the owner to "go ride" and see if anything turns up "inop" after a few miles (he just bought it & I got it running and tuned for him)

 

That makes me think it's the wire from a "Sender" of some kind. Does that bike have a "Temp Gauge"??

 

It could possibly be from the oil pressure idiot light, as the light is out when the key is on (engine off), illuminates as the start button is depressed, and extinguishes as soon as you release the start button (I attributed this to engine running=oil pressure, but didn't think about the fact is was out with the key on).
Funny thing is, I can't locate a probe with nothing attached to it...?
Perhaps the PO removed it?