AK hand
Your raise size is too big from the CO.
#1 The whole concept of betting is to get worse hands to call. By raising 4x, you might get the SB or BB to fold a hand like A
3
, where they would have called OOP vs you to a 3x raise size
#2 Your going to be opening hands like 87s, 22, QJo, 65s from the CO. You want a cheaper size with those hands, so you might as well raise your whole range to a smaller size like 3x
You have such a huge raise size preflop, when the SB 3bets you, he's probably going to have a tighter 3betting range now (I know I would). So when he checks, he probably has AA(1), KK(3), QQ(3), JJ(6), TT(6), maybe KQ/AJs/ATs/KJs.
So when he is c/c'ing flop, he either has a middle pair like KK, KQ or a monster like QQ or AA. The FD completes, you check behind. The river is a T and he ships. Well, he would definitely be checking KK or KQ for showdown value. Its very plausible for you to check behind an A on the turn. So that just leaves the stone cold nuts AA or QQ. AK is a possibility, but most people go ahead and bet AK. I could see villain checking though being scared of AQ. So if you discount half his AK combinations, that leaves 3 and 4 combinations of AA/QQ. And vs AK your only winning half the pot on a call, so its just a fold.
***I would also advise you the watch some training videos on either Deucescracked.com and read some poker theory books. Think it would really improve your game