So I am currently playing a human kineticist. He is first level.
Stats
STR - 10
DEX - 16
CON - 18
INT - 12
WIS - 12
CHA - 7
HP - 12
Fort - 6
Ref - 5
Will - 1
AC - 17
CMB - 0
CMD - 13
Atk - Air Blast: +3 1D6+1+4
Traits: Reckless (Just for acrobatics), Adopted (Eleven reflexes)
Feats: Point-Blank Shot and Precise shot
Several of the people in my game think the kineticist is overpowered at first level. I sort of agree with this compared to some of the other damage outputs with classes that have the same BAB progression. I have been reading other posts and say that it doesn't get any better. They say that they should limit the amount of times they can do a blast or decrease the damage or give bigger jumps in-between levels to gain damage.
I think the damage progression and damage out put is decent. Maybe make it so it it every 3 levels instead of 2 levels.
I don't like how many class skills the kineticist gets and how many skills per level. I feel this is a big blow to the class. This is my biggest concern with the class. I feel pretty useless when it comes to most skills compared to other classes. Definitely make acrobatics a class skill and maybe give them 1 or 2 knowledges. Then each separate element can have it's own skills. Maybe where one is replaced or gains a new one. So the kineticist gets 2 knowledge skills and depending on what element he takes replaces one of the 2. Or they get one knowledge skill and add one based on the element the choose.
As for burn, it sounds really cool. The fact that I can push the characters body beyond what it can handle to maximize what it can do. I feel like there maybe should be some sort of "pool" the kineticist can use to fuel some of the wild talents. So maybe similar to the monks ki pool. So maybe 1/2 level + Con. Then if he runs out of the pool then he takes non-lethal damage. Also if the damage can only be healed by 8 hours of sleep that really hurts the kineticist altogether. Especially in Society play. Most scenarios, that I have played anyways, there is no time to get the 8 hours of sleep. So by the time you get to the end you are already down on hit points. I have been reading up on the Metakinesis ability and as it seems pretty cool it looks like it hurts the class more then helps it.
I really like this class cause now I can actually build and air bender. ;)
Note - I haven't been playing but maybe for a year and a half so keep that in mind.
Quick experiment, to show why your damage isn't high.
Move your 18 Con to Strength. Throw a javelin. Same damage, more range. And now, you're also good at melee. Use a spear in two hands and marvel at 1d8+6 damage.