[SNOWBALL138]

.8 is a high AF for 63 vpip but not THAT high.
I think villain has 66 for bottom boat or some hand like A6 or 67 or T6. Sometimes he has a jack or something that you beat, but not very often.

You are increasing your chance of winning the hand on the turn by about 16% maximum (str8 draw is the biggest draw you could be facing), if UTG+1 has a str8 draw.
16% of the expected pot size by the river is 2.2bb.
2.2bb is nice, eh?
Hold on a minute though. UTG+1 doesn't always have a straight draw, and when he does, he usually won't fold it either! Sometimes utg has a much weaker draw, a hand with a jack in it or a gutshot like T9.

Also, you are often behind once you get checkraised, so you aren't actually increasing your equity by x%*expected river pot size, but rather (x%*y%)*expected river pot size.

X=the amount of equity that UTG has multiplied by the chance that he folds.
Y=hero's equity

I think your equity on the turn is way way too small so your raise loses too much value. If there were no pair on board, a raise would make a lot more sense, because you would want utg+1 to fold a 5-outer, and the chances that you are currently ahead would increase too.
Therefore, calling down is better than raising this turn. Also,you don't want to get reraised because you have outs against 66 (two sevens, and two kings).