$100 NL 6 max at Cake.

I just won a decent pot with KK vs 33 all in preflop. The guy was short though.

Very next hand. UTG raises to $3.50 (different guy). I make it $13 in the SB with [Ac]. UTG calls. My notes on him say "raised 86 UTG". I dont know much more than that about him. I assume anyone who raises 86 UTG is pretty LAGgy.

Pot $27. Flop [8h][5c]. I bet $21 and he calls.
Pot $69. Turn . He has $68 left. Do you just make the obvious shove? Or do you think theres any value in checking since if I assume hes a LAG, he will probably shove himself with any hand he got this far with...but might fold some of those like 98s or TT if I shove into him? Would a good LAG (and I dont know if hes good or not) check behind with 98s or TT...or with a flush draw?

Shove.

If he raises 86 UTG he'll most prolly stack off here with TT, JJ, AQ, KQ, maybe JQ and call with a FD.

I don't hate checking behind but I do hate the thought of giving a free card to someone when I have invested 35% of the effective stack into the pot.

It could be that he's not LAGy at all and is in fact a donk.

You have no postflop reads on him to substantiate your hunch that he's a LAG, so I'd just push and get called by lost of worse hands.

I prefer something like 40 on the turn...donks pay that off a lot more than just shoving...against a good player I'd shove. Against this donk, just bet 40. This is so standard though...the difference between betting 40 and shoving is SO small.