Super high idle

On my 82 kz750 i've replaced pretty much everything. The engine starts and for some reason if we let the idle sit at 2k RPM it shoots up to 7k RPM and I have to turn the bike off. Im thinking there must be an air leak somewhere. Any ideas? I've rebuilt the carb, new vacuum and fuel lines. I did notice the carb boots have some cracks in them because they are old and I am having them replaced. Just not sure if that is the reason for the idle to go so high like that.

New boots would be a good place to start. Make sure the airbox boots in the back are air tight too and that you have a good air filter installed. Also, check your throttle cable to make sure the carb throttles snap back to closed when you twist the grip and release. They should be a noticeable thunk sound as the throttles go back to the stop.

I have an 82 kz750e and it would idle high in neutral or the clutch in turned out to be air leak around the carb boot easy to test while running spray carb cleaner or wd40 around the boots ands carbs and listen for idle change