After replacing two exhaust valves and reconditioning the cylinders and valve seats my bike revs reallllllly high when it starts. Throttle adjustment is all the way out and the cable is not tight. The carbs sat in an awkward position for a month or two while the project went on. Where do I start trying to fix this?

The rest of the project was discussed here

Air leak would be my first guess.  Double check the carbs are in the carb boots correctly...I put mine on with the rubber boot folded up onto the carb openings once.

Try the WD-40 or starting fluid tests.

1  how does it idle while warmed up? 
2  does it only rev high when the choke is on? 
3  how many rpm's is it actually spinning?
4  have you tried backing out the idle adjustment screw?  it is between the carbs, on the bottom

Stuck choke would be my guess.

Today, it idled perfectly for about 2 seconds and then revved back up to 6000rpm, where it stayed until I turned it off ( 5 seconds or so). I did try the throttle during that time (it revved higher, so it's at least responsive) and I tried the choke (it revved even higher, maybe ruling out stuck choke? I'll check it anyway -- maybe it's half-stuck). I did struggle with the carbs getting onto the airbox a little so I'll double check those too. I turned the idle screw below the carbs as far as I could before it looked like it was going to fall right out.

VROOOM! Everything's working now, baby! Valve replacement job complete. BAM!

It was the throttle cable. On second inspection, it was, in fact, too tight. I adjusted the two nuts and we're in business.

Thanks for all the help everyone. You're the best.