[James282]

When he bets on the turn like that after a rainbow flop you are [censored]. The A is the worst possible card for his holdings you are ahead of - if he is truly unknown this one flies to the muck. Also, most people raise more before the flop. 55 seems to be a number that will entice many more callers than say 70 or 80 (there is a noticeable difference IMO).
-James