i agree with everyone above. your charitable act could come back to haunt you in a big way.
i've sold a bunch of bikes, and in the back of my mind, i always think about what will happen when they crash (notice the use of "will" and "when," not "might" and "if.")
the people i've sold bikes to, i trust enough not to bring any action against me, as well as being relatively responsible people who know what they're getting into.
i'd be very leary about giving a bike to an unknown person, with unknown skills, especially if it's the first bike you build, and haven't figured out the quirks and potential hazards.
if you wanna auction off something, and want it to be different, buy a regular bicycle and customize it with paint, etc, but don't put a motor on it.
and, build one for yourself, of course...