Vacuum lines

My kz1000 st has 2 vacuum hoses cabled tied to the frame, 2 others are capped & 1 going to the petcock, I’ve read they should go to so to some valve of sorts or to the airbox- airbox doesn’t have a  nipple & there is no valve either, should they be capped off,
tia

The two hoses tied to the frame are most likey the vent hoses.
They should not be attached to anything other than the carbs on the one end.
Don't cap off the other ends, just leave them open and strapped to the frame.

The other caps on the carbs are probaply vacuum connections.
One, or two are used for the vacuum to the fuel valve/petcock if equipped with a vacuum petcock.

Then there is the fuel connection/s to the carbs.

Some models have an emissions system, with hoses coming off the valve cover to a PCV valve, hoses then to the air box and carbs.
 

The Kawasaki Clean Air System introduces clean air from the air box into the exhaust ports. There should be a large hose from near the top of the air box that connects to a large vacuum valve, then splits into two hoses that go to the reed cages on the cam cover. Under the reed valves there are small ports into each exhaust port.

As rstnick mentioned, each carburetor has a vacuum port. The one on carb number two should be connected to the petcock. The port on number three should be plugged. The ports on one and four should join at the large vacuum valve  of the CAS, near the air box. I am pretty sure there is a decent diagram in the fsm for the other KZ1000$ that is in the file base.

The inlet manifolds should all have a rubber cap on them, there should be two vent hoses one between each pair of carbs, if you have a vacuum peacock there should be a vacuum stubb on carb number 3 body.

Not sure if this will be of help or not. The attached is a set of vm26ss carbs. I am unclear if your machine came stock with 26 or 28 carbs but either way the ports (vents and vacuum) should be much the same. As a note some carb sets have a single fuel inlet (between carbs 2 and 3) and some have 2 fuel inlets between carb 1 and 2 and between carb 3 and 4. Will say the vacuum port location on vm26 and vm28 carbs is the same, on carb number 3.

Keep in mind depending up what sort of carb holders (rubber flange that connects cabs to head) you have they may also each have a test (vacuum port) located on them. If they are not being used to operate some type of vacuum device they should all be capped.

You also mention the clean air system that bikes intended to be sold in the US had. I have included a pic (it is for the 550 bikes) that shows how it plays into this. If your machine has such it would be much the same.