When a snake percieves you as a threat, and it bites you and you move away, it sees that and it knows that when it bites you, you(the threat) go away. So that's why he will keep biting. What you need to do is get a thin layer gloves, from like Wal-mart, or something, some gardening gloves, then handle him. After a few attempts of him biting and you not going away he will eventually tame down a bit, how much depends on both you and him. Start out with handling him once-twice a week, then up the handling frequency. I hold my 2 snakes several times a week, except for the past month or 2 because of work and such, and mine are still as docile as ever, though my conda seems like she is getting a bit head shy, so I started with the handlings more frequent and she doesn't mind me petting her on the head anymore.