Identify pistons please

More parts from another parts lot purchased. I’m going to assume these are Kz parts. They came from a guy selling off extras from included in a ‘77 Kz1000 bike purchase. stamped 1.00 on dome. Inside skirt is +5, also inside skirt 7620. 71mm with 17mm wrist pins. 1045?

Those are basically two sets of OEM 1mm oversize Honda CB450T cast ART pistons.
A common mod back in the day prior to the availability of aftermarket big bore performance pistons for the 900.
Here's the very same i had in an early ex race Manzano engine that i initially had fitted in my Z1R and then later in my alloy cafe project .

 

zed1015 wrote:

Those are basically two sets of OEM 1mm oversize Honda CB450T cast ART pistons.
A common mod back in the day prior to the availability of aftermarket big bore performance pistons for the 900.
Here's the very same i had in an early ex race Manzano engine that i initially had fitted in my Z1R and then later in my alloy cafe project .

 
 

Thank you. 450 or 500? Do you know the CR, with Kz head? With J head? 

Not an expert on the CB twins but they are certainly CB450.
I looked into them over 20 years ago when searching for new rings after i aquired mine in a hoard of ex race parts and vaguely remember the 500 had the same bores but lower domes.
Not sure of the exact compression but will be in the region of 10.5 -1 with kz head.
J head will be 2 points lower compression.

Zed. I’d like to look at availability of rings. Is the 1.00 = 1st over or is it 1mm over stock?

1mm over