900 Head casting difference

[Chris71]

Hello, more of an interest point, does anyone know about casting differences between the 900's ?
I have a 74 a 75 and a 76 all have original engines but I've noticed that the 75 has a difference in it's head casting than both the 76 and the 74. They all are original 900 heads with the 6mm exhaust studs.
Any ideas.. see the pictures abit weird that it's the 75 with the odd casting so not related to early or late?

[zed1015]

Are you sure the head is original on the 75 ? or maybe the factory were using up some older inventory..
The head castings were originally designed to have an m6 bolt in that location which was never used and changed to a small rib on the later ones.
The bolt would have threaded into the head from below.
They never changed the barrel casting though so they all retained the undrilled lug where the shank of the bolt would have passed through..

[z2.john]

There are many slight variations on the Z1 heads. Picture here might help you. You can see it if you look carefully by the exhausts

[zapo]

For what it's worth, here's mine, late Z1B, engine number 825**

[Chris71]

There are many slight variations on the Z1 heads. Picture here might help you. You can see it if you look carefully by the exhausts

Super informative, my 1974 Z1A has an "4" my 1976 Z900A4 has an "5" but the 1975 Z1B has a "2" so definitely an early casting? All the bikes have their original engines as I have all the paper work for each one.
The Z1B has an engine number lower than the frame number by 61 units which I understand is not common its build date is 1/75 so maybe a new year clean out at Kawasaki, it is also a low mileage bike so find it hard to believe that it's had a head swap but you never know..

[z2.john]

The TK-2 castings were generally used on the earlier Z1 range. I have never seen one on a 1975 Z1B but that's not to say old stock was being used up

[z2.john]

I'm no expert on later heads but it looks like your 1974 pic (TK-4) maybe has a Z1000 head fitted? Has a 8mm to 6mm stepped stud been used?

[Chris71]

I'm no expert on later heads but it looks like your 1974 pic (TK-4) maybe has a Z1000 head fitted? Has a 8mm to 6mm stepped stud been used?

No it's got 6mm studs however it had a few broken off studs and then was drilled out damaging the internal theads so it was repaired by having inserts installed, very tricky as the previous owner had drilled the 6mm studs off centre making a oval mess. Luckily was rectified with 8mm to 6mm inserts on the manged ones..

If your saying TK 4 is off a Z1000 wouldn't that mean that Z1000's were using an early casting if it had a TK 4? I recently had the head of the 76 (TK 5) and that is stapmed 76 underneath..

2.John post there were "4" castings for the Z1 so that would figure, I'm now confused....