The main problem I'm having is that I would need to crank my idol screw all the way in for it to even idol, then when I turn the air screw out it keeps idling up.  I started with a 37.5 pilot and then went to 30 then 25 all with the same results.  I went to the local shop today and grabbed a 15 and a 45, it's acting like it's rich so I tried the 15 today and then it started idling with the idol screw turned out like it's supposed to and I could idol it up a ways now with that screw.  The air screw all the way down it fumbles like normal but it seems to keep idling up when I back that air screw out even past 3 turns.  Seems much better on the low end throttle response though and the idol is better, it was kinda bogging on the low end and not very responsive yesterday with the 25 pilot. Seems a lot of people run a way higher pilot most of the time if i'm not mistaken.

My quad has these mods.

No air box and k@n right off the carb. 
Boysen Rad Valve and carbon reeds.
.60over
Fmf pipe and silencer.

I guess my question is…Is having a 15 pilot crazy?  Would going even lower be just out of the question? It's super cold here today in Michigan as well, like 4deg. 

Does that mean the carb is just shot then?

I rebuilt this carb so the needle is new along with all the stuff that comes in the carb kit is all new on the carb.

So the pilot jet works though that as well I take it? 

Sorry for my lack of knowledge about this. 

What year Carb 87 or 88+.    you're way below normal jetting, sounds like you have a plugged port and the pilot air circuit is not drawing at all.

I am not sure if your confused about the operation of the AIR SCREW also. When you turn it in the idle should get lower or stall. Backing it out allows more Air into the system creating less vacuum to draw fuel up into the venture. The way you're explaining this sound like you're used to 4 stokes.

Set your slide height to 2-3 mm this puts it at @ 1/16 throttle and get the pilot and Air screw working in this range.

1990 is the year.

I thought there was a point with backing the air screw out that it should rev down again or is that wrong?

Also when setting the slide height, do you set that height with the idol adjustment on the side of the carb, or open up the throttle on the handle bars and adjust it there? Also do you measure where it's flat when looking into the carb cause the middle has the round part on the slide that goes higher?

Pro,  the more you back the air screw out, the more air you let in.

Use the idle screw (thumb screw) to set the slide height.  Be sure that your throttle cable is adjust correctly so that the slide is able to go all the way down.  after setting the slide height, adjust the throttle cable so there is no slack.

Pull the boot off connecting the carb to the air box so you can see the slide while adjusting.  again, be sure that the throttle cable is adjusted out so that the slide rests on the bottom of the carb.  From there, screw in the idle screw until the slide raises about 2-3mm like Ice said. 

RWV brings up a good point.  Once you set your slight height, never touch it again.  Use the air screw to adjust idle.