First, a little background:
For our first engine iteration we will be using sectioned ZX-6R cylinder heads to enable us to develop a stable and low loss bottom end without chasing induction, combustion and exhaust issues. To a large extent a 4 stroke engine makes power above the head gasket and loses power below it. Since we have complete cylinder head and cam assemblies and tuning info from the Attack Kawasaki team once this engine is running on the dyno we can clearly see how our short block design stacks up against a standard I4. Once we get a efficient and reliable short block assembly we can start on a bespoke cylinder head assembly. In order to get to this point we need to cut up an existing head and seal the exposed water and oil passages. The question was do we use a bolt on or weld on cap plate. After getting some advice from Ian Drysdale we decided to use the weld up technique for maximum reliability.
Scott Kolb of Kolb Machine, was willing to do a quick test head and see how the passages would seal up and the resulting heat input affected valve seat retention and deck flatness. A cheapie eBay head served as the test mule and taking it to the bandsaw resulted in the following part to be welded:
Scott proceeded to fabricate cap plates as shown:
He then beautifully capped both passages with stack of dime weld beads:
Excellent work for a proof of concept. Once we do the final heads they will be put on a machining fixture to face the valve cover sealing surface.