Valve stem at the top of front forks

I have a 1980 KZ1000 Shaft. When I bought it a few months ago, I noticed that there was a valve stem at the top of each front fork. They don't look stock, and I see no mention of them in my owner's manual. Does anyone have experience with these? I'm assuming it is some type of suspension control. I put a pressure gauge on them and they are showing no pressure.

Are they stock, or has someone modified the front forks? I'll attach a couple of pictures for clarity...

Here is the second picture...

If you put air in them use a hand pump not a compressor. It will not take much air pressure to blow the seals. As far as stock I could not tell you but others might be able to help you.

Kawrickrice is correct, add air with a bicycle pump. It is a low pressure system (8-10 lbs tops). And you are also correct...it is not stock to your bike...which means there may be no balance tube between the forks...which means you have to manually match the air pressure in each fork...handling will be troublesome if the pressures are markedly different...or you could leave them empty of pressure...that's how Kawasaki originally designed them As an aside, what does that screw clamp in the picture do?

Thanks for the advice, guys. I figured I'd better not blast it with the compressor until I figured out exactly what it was. The bike rides fine now, so I'll probably just leave it alone... Although the tinkerer in me really wants to mess around with it. We'll see...

Mcdroid, the screw clamp is part of the mounting system for my windshield (Streetshield EX, works great).