Popping, high idle, surging all overnight

Ok. I have an 84 ZX750 GPZ that I just got hold of. I traded my KZ650 for it a week ago and it ran like a dream the whole time, no problems, started right up, idled fine everything. I walk out to the garage this morning and the carbs have leaked gas out onto the motor. Couldn't tell you how much, but it was enough to run down the sides of the motor. I started it and it was fine, then as I let it warm up the idle went up to 4000RPM (no choke) and started popping. I put it in first and turned it around to get it back up the driveway and the motor was surging. When the revs dropped to around normal idle it sounded and acted fine, but any higher than 3000RPM it would start popping again. Any ideas?

Sounds like an air leak. Check for missing rubber caps that seal the vacuum tubes/ports. I'm not sure if your intake manifolds or carbs have them, on my bike they are on the manifolds.

The gas may have loosened them up and they dropped off. If you can't find yours then buy some vacuum caps at the auto store, I think it's 7/32".

Thank you. I'm off to try it now. Any ideas as to what caused the leak?

Ok, I think I found the vacumn points, and there is nothing there, cool. I also discovered the source of the leak, my petcock does not shut off. Can anyone walk me through how a vacumn petcock is supposed to function so I can try to troubleshoot this thing?

Ok, I "fixed" the petcock issue, and put the whole thing back together and surprise! It still pops. I started it on full choke, let it run a minute, put to half choke and the revs dropped from 6000 to 4000. I let it sit another minute, and took the choke off and nothing changed. It still sat at 4000RPM. The bike is behaving like it is on half choke all the time. I looked around the mechanical linkages on the exterior of the carbs and everything looks to be in working order. Anyone care to lend an opinion?