questionable on all but one street?

[Apocalypse]

POKERSTARS 5/10 (6 max)

Im on the button holding A/images/graemlins/club.gif 6/images/graemlins/club.gif

All call, I call, SB calls, BB calls

flop:

6/images/graemlins/spade.gif 4/images/graemlins/diamond.gif 4/images/graemlins/spade.gif

Checked to CO who bets, I raise, SB coldcalls, the rest folds

turn:

7/images/graemlins/club.gif

checked to me, and i check!

river:

K/images/graemlins/club.gif

SB bets, CO calls and i fold

results in white below:
<font color="white">
SB shows 4c 2s and has three of a kind fours
CO shows 6c 5h and has one pair, sixes
</font>

Regardless of the results, fire away /images/graemlins/cool.gif

[Zele]

No reason to give up on the turn. Overcards or a flush draw are more likely than a 4, and definitely justify continuing.

[Apocalypse]

woops, 4/images/graemlins/spade.gif was a 4/images/graemlins/heart.gif, otherwise a bet would've been auto (and perhaps still is) i agree

[Ikke]

Since you changed the 4s to a 4h it becomes closer, but I would still bet. Would he check-raise you on the turn with a worse hand? I think this typically is a hand where you should charge overcards and straight draws, but can make a good read if you get check-raised on fourth street and let go (you likely have only 2 outs if you get check-raised; a pocket pair would likely 3-bet on the flop or not check-raise the turn IMO).
If he can check-raise with worse hands it will become more difficult, but mainly because you should decide if its profitable to call a check-raise down.

I agree with your river fold after the overcall.

Regards