Newly acquired kz750 oil leak, white smoke

You can do some crack test in the suspect and degrease area.
In my company we checked suspected rollers surface condition ( for cold rolling mills ) for hidden cracks.
Color RED sprayed on to penetrate the crack, then wipe away after 3 minutes.
Color WHITE sprayed on as a contrast medium, RED penetrate out of the crack and discolored WITHE.
Crack found, Bingo



BTW: The mayonnaise that you see ( Oil / Water mix ) is called Emulsion.

Thank you all. I did have the manual for my bike-KZ750H2 1981 from the previous owner.
Will take yall advice and inspect the valve area before tearing down the whole engine.

You can do some crack test in the suspect and degrease area.

That a brilliant idea.
Finger cross that It's just valve gasket leak.
Will update the progress.

Hi yall. After carefully inspecting the whole engine, I finally found the leak.
yall are right when saying that the leak is from the valve gasket.
I attached some pictures
For the missing piece on the "stripped side", I didn't hear any noises in the engine to indicate that the broken pieces got into the engine, so that is a relief.
I can find a new valve cover on Ebay for $30, but I am wondering if I can use JB weld to fill in the "small crack" and shape the JB weld to fit the broken piece on the "stripped side".?
Again, thank you for all inputs and comments.

The loosen screw of the camshaft sprocket cut its way slowly into the valve cover and cylinder head until
she fall out and smashed into crack area of the valve cover. Never seen before.
Take a deeper look to the head find more / or to avoid any possibility of more hidden damages.
Buy a new valve cover on Ebay for $30, go the safe way.

Just got some time off to continue working on this bike and discovered a problem with the camshaft chain tensioner. It seems like the previous owner has replaced the OEM tensioner with some aftermarket tensioner. See picture for more detail.

Per manual, I have to take out the camshaft chain tensioner before disassembling the camshaft. With this aftermarket tensioner, I really don't know how I should approach. The ultimate goal right now is to disassemble the cam shaft, cylinder head to inspect inside for any piece of valve cover that was cut by loosen screw of the camshaft sprocket.

Any advice is welcome. Thank you