Purchased a used enduro motorcycle from a person but did not receive a
title just a bill of sale.  I'm looking to get a tag in Florida.  The
bike is street legal but I am unable to get a tag without a title and
all the offroad riding in my area requires a tag.  The person I
purchased the bike from is unwilling to return my calls but I do know
he did not purchase the bike new.  The bike was never registered in
the state of Georgia using a vin lookup with the DMV. I've found no
way to find the previous owner. It is possible it has never been
registered. Tried a couple of sites like carfax to try to find the
history but never had any luck.  The bike is a 1993 kawasaki KE100. 
Is there a way to get a tag so that I can actually ride the bike
instead of using it as an expensive lawn ornament?

http://www.hsmv.state.fl.us/dmv/faqtitle.html#7a


This might help you. There is a section also on how to find out the past owners.

Hi,
You might try to contact on this site and see if serial no. can lead
to the original purchaser:

http://www.kawasaki.com/content.asp?url=/kawasaki_aux/our_company/intldist.asp

Good luck, Myoarin