Cylinder head reboring or change jug

Good evening,
My cylinder walls have 4 deep groves, as a result of oil ring that broke.
I have 2 options:
1. re bore to 0.5 or 1mm depending on the depth of the groove
2. Buy a second hand cylinder jug.

The problem with the 1st is that I cannot find pistons to that size and rings....

Do you think that old pistons with new rings will go ok in an SH jug?

My bike is a 1978 KZ400 B1

This is the jug :http://www.ebay.co.uk/itm/1978-Kawasaki-KZ400B-78-KZ-400-B-Cylinder-Jug-/232095318168?hash=item3609f58098:g:MRkAAOSwmfhX6R66

Pics?
Steve

can i change piston part number 13029-1006 with the older model 13029-070 .
I don't have any other option as cannot find the 1st one to buy...

Your bore / stoke is 64,00 mm x 62,00 mm on all KZ400 models excepted the KZ440 with 67,50 mm x 62,00 mm
Source: kz400.com/TechnicaldataFrameset.html

found two sides where you can buy over size piston and rings

www.cmsnl.com/kawasaki-kz400b1-1978-cana...t/51457.html#results

www.scheuerlein-motorentechnik.de/motorr.../Z400-Modelle/Z400D/

Thank you very much Scirocco but on the first site they dont have them. And on the German one they do but they are for the 75-78 model not mine. As I stated before. I dont think I have a choice and ill buy the old version ones's , as I cannot find the proper ones anywhere. part no. 13029-1006.
Thanks for the help

Hello Sharky, how did it end up?

I'm in middle of motor repair of my kz400 1979 and im looking for 1mm oversize pistons and oil rings. But i cant find it anywhere. However i found set of +1mm piston and oil ring for 1976-78 kz400, part number 13027-066. Pistons have sligthly different design, but bore and stroke was on all kz400 same, so it might work? What do you think guys?

Please see the pics. Piston with round head is original for my model and piston with flat head is for older models..

Yes, those pistons will work.
Another alternative is to take it out to 67.5mm and make it a 440.
The sleeves will go that far.


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The head and the cam are the same between the late 400 and the 440.
About the only things that are a hold over from the early engine is the
kick start cam chain.


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