set fills on turn, bet how much?

[fathertime]

.5/1 nl

villain 140; I cover.

4 handed. Villain is a bad calling station. I'm 20/10. Villain has called me down twice with marginal 1 pair hands.

Villain raises to two from co. I call on button with red eights.

flop comes k8tr (8 pot)

all fold to me; I bet 7. fold. fold. Villain calls.

turn t (22 pot)

Villain checks to me. I doubt he has a k--he would have bet on flop. He could have a t; pp; nothing.

Bet? If so, how much?

Check?