1977 kz400 cafe project.... help?

Hello, I a new to the fourm/ any fourm lol. What I do know is there is a lot of knowledgeable people on them so hopefully I can get some help. First I share a little info on my build, this bike was my first back in 04 and has had a rough life since. It was stored in my dads damp basement for 8 years. As you can see in the pics I have taken it back to life and have spent countless hours powder coating , cleaning or replacing absolutely everything.

Now the question I hope I can get some help with;

I had the top end apart and powder coated it, bit now that I have it back together it leaks. Followed all the steps in the manual to a t. The compression is great and runs super smooth with the new mikuni carbs. I can see bubbling around the head gasket. I never replaced the o rings that fit in the head gasket for the oil ports, can that be the issue? Sucks to have to haul it apart again lol but that’s it, any help much appreciated

Go to KZ400.com and start reading.
The oil leak is a design flaw of the early KZ400 engine.


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I had a similar issue with my 76 kz400. I rebuilt it and oil/gas was bubbling from head gasket. After some research, I replaced 6 of the 8 cylinder stud bolts, bought new style kawasaki gaskets and o rings, and I took the head to a machine shop for them to make sure its not warped. They refinished the surface for $35 overnight.

I have not yet put my bike back together but I'm expecting, and hope that this solves it. It was a kawasaki service bulletin mentioned on KZ400.com; if you do it you need to make sure you buy the new parts per the new product codes in the service bulletin.

k1z947060 wrote: I had a similar issue with my 76 kz400. I rebuilt it and oil/gas was bubbling from head gasket. After some research, I replaced 6 of the 8 cylinder stud bolts, bought new style kawasaki gaskets and o rings, and I took the head to a machine shop for them to make sure its not warped. They refinished the surface for $35 overnight.

I have not yet put my bike back together but I'm expecting, and hope that this solves it. It was a kawasaki service bulletin mentioned on KZ400.com; if you do it you need to make sure you buy the new parts per the new product codes in the service bulletin.

Here you go...
"Top end oil leaks. Kawasaki service bulletin"
kz400.com/KZ400D3lFrameset.html

Well thank you very much , I will look into getting the proper orings and gaskets.. appreciate it!

Dark_customs wrote: Hello, I a new to the fourm/ any fourm lol. What I do know is there is a lot of knowledgeable people on them so hopefully I can get some help. First I share a little info on my build, this bike was my first back in 04 and has had a rough life since. It was stored in my dads damp basement for 8 years. As you can see in the pics I have taken it back to life and have spent countless hours powder coating , cleaning or replacing absolutely everything.

Now the question I hope I can get some help with;

I had the top end apart and powder coated it, bit now that I have it back together it leaks. Followed all the steps in the manual to a t. The compression is great and runs super smooth with the new mikuni carbs. I can see bubbling around the head gasket. I never replaced the o rings that fit in the head gasket for the oil ports, can that be the issue? Sucks to have to haul it apart again lol but that’s it, any help much appreciated

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Nice Project you have