It's a wire wound ballast resistor. I did investigate it's purpose when rewiring my Zed and then figured it was best put in the not required box in teh hope that it will be worth lots of money one day
I have a feeling it might have been something to do with one Kawasaki's many efforts to stop the bikes blowing headlight bulbs, but it just made 'em dim.
The Old Gurl has done well over 3K miles since resto and all is working well and I have yet to blow a headlight bulb, despite keeping it on at all times
So bottom line - store it carefully in case it because valuable one day

Ralph Ferrand
Z1000A1 (1977), Z1300A5 (1983), Z900A4 (1976) GPZ1100 Unitrak (1983)(project), RD250B (1975)(project), ZRX1200R (2005) DT175MX (1981) YZF R6 (1999)
http://www.bikerstoolbox.co.uk