I do not believe it is wrong to look at boys and enjoy their beauty. I think it is wrong to lust over boys. The difference is in what you are thinking about. If you are thinking about how beautiful he is, then that's ok.

Enjoying the beauty of a boy is no more sinful than enjoying the beauty of a sunset, a waterfall, an exotic bird, or any of God's other beautiful creations.

If you are thinking about how you'd like to take off his clothes and.... then that's not ok.