My ZN700 has Keihin carbs and the idle mixture screws are set at 1 1/2 turns off the bottom. And initial setting of 2 turns out would be a good starting point. How did you clean the carbs. When I cleaned mine recently, I just removed the diaphram covers, fuel bowls, and the jets and emulsion tubes. Did you remove the plastic jet plugs and clean inside? Then I used a weld tip cleaning kit to poke through all the holes in the jets, emulsion tubes, and carbs. I also sprayed carb cleaner into all the orifices. That worked well. Before cleaning the carbs, I did put a lot of Gumout with PEA in the gas and kept running it daily and that started the cleaning process but it wouldn't do the entire job so I ended up removing the carbs.
1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
2007 Yamaha Royal Star Venture