Help! KZ400 oil leak (1976)

Been noticing after a ride that is see something leaking and figured it was has out of the right carb bowl so I'd started letting it run itself out of gas before I parked it for more than a few days. That was until today when after a short 20-30 min ride I see what's clearly oil in all the same spots. Any idea where to start in trying to find/fix the leak?

Clean it off with brake cleaner after noting the highest point you can see oil, then dust that area with talc and run the motor again until it starts leaking. You should be able to pin point the leak as the talc will stop the oil "running"

Thanks and nothing in that area to worry about getting either brake cleaner or talc on?

If your brake cleaner is chlorinated, then I recommend keeping it away from rubber bits like the cute little cap on the oil pressure sensor. 

Could be coming from the oil pressure sensor, check under the cap. Pull the cap, start the engine, you’ll see it squirting from the top of the oil pressure sensor if that’s where it’s coming from

Either way you will need to clean it up to learn what the issue is and to keep it from getting any worse. There are several things that could be the issue. Keep in mind oil leaks, as the bike moves through the air, tend to flow backward and from high to low.

I would immediately suspect the oil pressure switch. They are NOLA but there are a few new and used ones on eBay or, you could replace it with a gauge or plug it. The part number is: 27010-1157

Take a good look in and around where the red arrow is pointing. 
Some dampness appears to show just below the cylinder head...need to rule out that area as a possible leakage source.

Yes, I didn't see that earlier but it surely could be from the head gasket area.

If it does turn out to be the oil pressure switch, yes, they are not available through Kawasaki any more. As stated earlier NOS are available on ebay but are pricey when I looked, what I found that does work is kawasaki part number 27010-0818. It is readily available. I got mine form a kawasaki lawnmower dealer. It screws right in, pressure range is correct, just the wiring terminal is different. if you don't mind putting a different connector on your wire it works great: