720cc kit for 11/78 z650C

When I purchased my bike approx 17 years ago the seller gave me a box with what he said was a 720cc Wiseco piston kit, it has been in my shed cupboard since then.
Now that I am doing a major rebuild I am thinking of using it but have run into problems.
The kit came with no documentation, just pistons, pins and rings so I have no directions for the machine shop.
I looked at the Wiseco website and it seems this kit is no longer available so no help there.
The Wiseco part no on the pistons is 4021 and the only reference I could find was on ebay and that site say's that these are for a CB750/4.
I have measured the pin height, pin diameter and deck height and all seems good apart from the obviously enlarged crown and slightly longer skirt length, they also weigh 30 grams more as is to be expected.
I am hoping someone here has fitted this kit in the past and can answer a few questions for me.
1) Is this kit right for my bike.
2)if so are these pistons cast or hypereutectic so I can determine bore clearance and ring gap.
3)was there enough liner material left on the bottom of the liners to have a slight taper to assist fitting.
Thanks in advance for any info anyone can provide.

I think you'll find those pistons are forged and 65mm. Those pistons would be an 836cc kit in a Honda CB750. From what I've read, Z650 pistons were used in Honda CB750,s too {somewhere around 760cc using stock Z650 pistons in the Honda} . I know nothing about the maximum bore size on a 650 but as long as you have enough wall thickness on the sleeves , and plan on using the pistons, any reputable shop that does re bores will only need the pistons to measure for boring, tell them they are forged. In reality, if they know what they are doing they should know they are forged.

Thank you for the info 750 R1. Yes they are 65mm and that fact alone had me worried as it's 3mm over stock, looking at the liners it looks to be too much to do safely.
I have been using the same machine shop for 35+ yrs as part of my trade and trust them implicitly but don't expect them to do my research, all they want is my expectations of parts supplied and the pedigree of the parts and some form of documentation which I don't have.
Your input is much appreciated.

Cheers
Mc Tavish.

Someone on here has one but not sure who (a 740 too)........... back in the day they offered 740cc and 720cc and then switched to only 700 kits. Looks like a good sized dome too. Could be 12.5 to ones but I can't say for sure and could be off on that. I know .002 bore clearance is what Wiseco will recommend. I'd try e mailing Weisco. I would think they were popular enough for them to keep up on them.

Would be a little thin and pushing it but more than a few were sold along with the next size up to.......... Just searched and found out Baldy did a 720 kit before he went big and I know more searching with bring more up.

Thanks KZB2 650 for your info. (wow 740 is seriously pushing the limit)
I have emailed Wiseco but no response after 4 weeks, maybe covid 19 thing.
.002 sounds right to me for piston to bore clearance, funnily enough when I was an apprentice we were taught that air cooled 4 stroke engines should have twice the clearance of a water cooled engine. Who am I to question the Japanese about how to build an engine?
Thank you.

Cheers.

Mc Tavish.

that is a 720 kit 10.25.1 cr set clearance .002in you will be good put 25+ of those kits in back in the day when I worked for Kawasaki shop be sure to get piston pistons cleaned up good looks like you may have to replace the pins though.

Thanks DFIGPZ, just what I needed to hear!
The pins do look pretty shabby so I will see what I can sort out regarding them.

Cheers,
Mc Tavish.

So what was the final call? 836 or 720 ?

TheWhiteDevil wrote: So what was the final call? 836 or 720 ?

Both, if used in a CB750 they'd equate 836cc, if used in a Z650 they'd be 720cc .

Hi, yes 720 it is, sort of,
Using V=pir2h
A CB750/4 with 61x63 fitted with 65mm pistons would be 836.2 cc
A z650 with 62x54 fitted with 65mm pistons would be716.76
750 R1 is dead right and knows his stuff.
Upon the advice of DFIGPZ I am going ahead with it seeing he has fitted many of these kits with no problems.
Will update soon.

Cheers.
Mc Tavish.

Just picked up my parts from the machine shop, very happy with results.
It wont be long before I can start building now, just a few bits and pieces to come!