Bite him back (lightly) It works..I've done this to Kelsey and she looks at me with disgust..like "mommy how could you?" and it works. At least for me it did. Now she only play bites but when I have enough that's all I have to do.
Also you could try something like the bitter apple. Like when he bites go get it and rub a little in his mouth and he'll associate biting with the bitter apple and hopefully stop!