TOPIC:

First, great pictures by the way.

I have 2 heads here and both show the same indications as everyone else's so no point in throwing in more pictures. All 12 pistons I have here have the same rough casting on the crown and I went and polished them up to reduce the possibility of detonation.
I suspect these indications are conducive of this cylinder head. Possibly the coolant passages in that corner don't flow as well as the other parts of the head and leaves a hot spot in the head. That combined with the flame front development and then exiting of the exhaust gases.
All things considered, I can live with it. The VW 1.6 and 1.8 turbo diesel engines had a known design flaw and the web between the intake and exhaust valve seats would crack. The flaw was so common that they had a measurable spec in the service manual and if the crack developed bigger than X, then you replaced the head.

Yeah, all this make you wander... The casting is pretty rough in some areas. There could be lots of clean up done, including some reburring. All four cylinder blocks I have showed significant differences, especially in the water pump area. In the head, areas behind valve seats are quite inconsistent from valve to valve.

There was a NOS brand new head on eBay a while back. I wanted to compare but it's gone. At the end, there is nothing much we can do, except polish it a bit!

Gents, the plot thickens...
It would appear that this OEM head (NOS never been fired), has the same irregular casting marks in the combustion chamber - in this case, #1 & #2.
So... it would seem, a very common manufacturing defect...

A1That is remarkable and thanks for posting. Hard to believe they didn't alter the mold to accommodate that issue and leave enough material to machine out the irregularity.

You're in a unique position to provide us with some what I consider to be critical information here. One of my biggest bitches is that used heads/valves/ shim packs gets us to a point where we run out of available shims down at the 2.00 shim size and I think when Kawasaki machined the new heads, they didn't care if they left the head with enough material so that we had most of the shims available for servicing. If I'm correct, when you get this head assembled, the shims required will be in the range of 2.40 or smaller. If they had done their jobs correctly, the new head with new valves would have required shims up near 2.80- 2.90 sizes leaving us with all the shims from 2.90 down to 2.00 for wear and tear service adjustments.
Would you please do me (and all the rest of the members) a huge favor and after you get this head assembled, report what shims were needed to set up the head.
Thanks
KB

Frank833 : It is possible that this spots are “as cast” and the casting there was too low so it was not machined when the combustion chamber was.

I tend to agree at this point. . Hard to believe Kawasaki would allow this to pass. The piston domes however are more of a puzzle. By the photos it looks like the domes were left as cast. I would have expected to see the piston tops machined and fly-cut for valve head clearance. Otherwise - can't understand the poor quality of surfaces.
Don't know if this is relevant but as I just did a valve clearance adjustment I'll submit my shim/clearance specs. Note: Engine has never been apart and has 84,000+ kilometers.

Per the Manual Pattern and cut from a foam camping-ground mat. Superior to a rag which will inevitably get caught in the chain and gears when rotating the crank and much better "sealing" then a piece of card-stock. Plus .......reusable !

Thank you A1 for posting these photos and confirming it's all in the process of how they made these heads. Same goes for pistons, why they were not nicely machined at the top is a mystery to me, except time and money saving. Overall, bikes build like tanks but welding and casting somewhat mediocre. I wonder it this fits the era in other Kawasaki bikes of the time.