If you want to get more money in, you should have bet less on the flop so worse hands (Qx, 64, etc) can call you. On the turn, a straight just completed, but it's still doubtful that he had exactly 64, so, I'd still bet out to induce a call for the same reasons he called on the flop. Make him pay for his draws and think that his Q9 is good. River, valuebet 1/2 pot.