1975 KZ400D Oil Leaks even after service bulletin

Hello All, Working on my first project KZ. I got it running and it leaks oil terribly from the head gasket area. I complied with the entire service bulletin regarding oil leaks. I used genuine Kawasaki NOS parts. Everything torqued to spec with calibrated tools. Performed the 5 minute run and complete cool down and retorque. I start up the engine yesterday and oil is leaking out between the cylinder head and cylinder on the back side of cylinder one at the gasket. It's bubbling out.

Are there any technicians who have successfully stopped an internal oil port kz400 from leaking oil? At this point I'm contemplating sending it to a qualified experienced person for repair. Are there any technicians in the SE WI area that would like to inspect and repair this engine? I could ship the engine if that would be helpful. I'm an aircraft technician by trade, but disassembling and reassembling the engine again to have it leak oil again is not sounding attractive. Is head warping common? I'm very frustrated and just want to ride.

Brett

Back when I was a Kawasaki Tech I did a few many moons ago I am in Maryland .

Did you check the warpage with a straight edge at the head and block?

I did not check the cylinder or cylinder head mating surfaces for true. It didn't even occur to me to do so. I've never actually seen a warped head or cylinder mating surface in real life, but then again I'm not motorcycle tech. Is this a common occurrence in the air cooled motorcycle engines?

Very common, air cooled engines burn up in traffic. Head and block deck warpage is the first thing to check when tearing down the top end -- especially if an oil leak was the problem. Hot enough and there may be a crack.

Not familiar with your engine, but it looks like an oil passage at the rear outer of the cylinders in the part's diagram. Is that where it's coming out?

www.partzilla.com/parts/search/Kawasaki/...KZ400+-+D/parts.html

The oil is coming out within an inch or two of the port. Nice call. I"ll check it out.