Proper head gasket for my 650

I have a 79 650 SR that was passed on to me as a project. The PO told me it was bored out but did not say how big. I have the top end off taking care of a stripped barrel stud. Another subject all together. His comment was I needed to buy a larger head gasket to allow for the larger bore diameter. When I search this out a few places they say the 650 and 750 are the same so why would I need to buy a special head gasket? It may be simple but I just don't get it. The bore now is 64.5mm wide.
Thanks for the help guys.
Great site by the way.

The 750 gasket will work.

That's a good question. According to Kawasaki.com all the engines in the bikes listed below use the same head gasket. It is also worth considering that the KZ650 and KZ750-4cylinder engines use the same connecting rods, so I would think the difference in displacement must be the result of the KZ750 having a larger bore than the KZ650 - yet they use the same gasket. In fact, the specs I've seen show that the KZ750-4cylinder has a 66mm bore. Ed

KZ650-B1 (1977)
KZ650-B2 (1978)
KZ650-B2A (1978)
KZ650-B3 (1979)
KZ650-C1 (Custom) (1977)
KZ650-C2 (Custom) (1978)
KZ650-C3 (Custom) (1979)
KZ650-D1 (SR) (1978)
KZ650-D1A (SR) (1978)
KZ650-D2 (SR) (1979)
KZ650-E1 (LTD) (1980)
KZ650-F1 (1980)
KZ650-H1 (CSR) (1981)
KZ650-H2 (CSR) (1982)
KZ650-H3 (CSR) (1983)
KZ750-E1 (1980)
KZ750-E2 (1981)
KZ750-E3 (1982)
KZ750-F1 (LTD Shaft) (1983)
KZ750-H1 (LTD) (1980)
KZ750-H2 (LTD) (1981)
KZ750-H3 (LTD) (1982)
KZ750-H4 (LTD) (1983)
KZ750-L3 (1983)
KZ750-N1 (Spectre) (1982)
KZ750-N2 (Spectre) (1983)
KZ750-R1 (GPz) (1982)
ZX750-A1 (GPz 750) (1983)
ZX750-A2 (GPz 750) (1984)
ZX750-A3 (GPz 750) (1985)

That got my attention too. I worked Kawasaki parts for 31 years. Back in the 80's, I know Kawasaki had a part number just for the KZ650 four head gasket. Don't remember the number anymore. The 11004-1107 was for just the KZ750 four. And the 750 Turbo used a 11004-1101 head gasket. I see the 11004-1107 is NLA, but the Turbo gasket is still available!!!

So I guess I will stop over to my local Kaw. dealer and have them look both numbers up.
I wonder what the dia. is on both if anyone has that info. 650/750

Jburkart wrote: So I guess I will stop over to my local Kaw. dealer and have them look both numbers up.
I wonder what the dia. is on both if anyone has that info. 650/750

I have a NOS KZ650 head gasket; part number 11004-1037. The diameter of the holes is 64.83mm. This part number has since been superseded several times (see image below from Kawasaki.com), but I don't know if any changes were made to the size of the holes in the later part numbers. Ed

Follow up on the head gasket question. So I went to my local Kaw. dealer and they did tell me the part number would be the same but it had a nice $110.00 price tag on the head gasket alone. Ouch!
So after searching I've decided to go with the Z1 guys. I looked on eBay forever and just do not have the experience to decide who has a decent set or who to trust. After hearing their name brought up on here several times I went with them.
I was on the GS forums for a while with my GS750 and they all seemed to dislike after market gaskets. Is this the same with Kaw. gaskets or can someone share their thoughts on this subject please.
My last question is, if the stock bore on the 650 is 62mm and the 750 is 66mm and mine reads 64.5mm does that mean this bike is bored to say a 700? Don't make me use my KY. math, just help me out please.
I love a project where you really don't know all that has been done to it. Trial and error and cash it's looking like.

No eBay APP ID and/or Cert ID defined in Kunena configurationOuch is right! Just buy a genuine Kawasaki head gasket from eBay - $30 delivered. (They screwed up the model name in the title, but notice the part number is 11004-1037.) Ed