The only legitimate bi-curious superhero would be Wonder Woman.
What about Hawkgirl?
Superman was flying around Metropolis when he sees Wonder Woman on the top of her apartment building, naked and spread eagle. He swoops down, drops his tights and has at her. And faster than a speeding bullet, he comes and goes. Wonder Woman says, “What the hell was that?” The invisible man says, “I don’t know, but my a$$hole sure hurts!”