Are these OEM pistons or not?

Got my KZ900 top end disassembled and I have no idea what was done to this engine in the past by previous PO's. Need to purchase the required measurement tools to figure out what size I got. Anyhow, the pistons that are in there now are have ATP stamped on them. Is these standard OEM pistons?

Edit: My mistake, I looked at the pistons again and they are ART not APT. I guess its time me to start wearing bifocals, lol.

Ya they sound like they are stock. I believe my stock pistons said ART on them.

Powerstroke_fan wrote: Ya they sound like they are stock. I believe my stock pistons said ART on them.

Stock KZ650 piston:

Yep, Kawasaki thinks the stock ones are a work of "art" :woohoo:

OldSchoolZ wrote: Yep, Kawasaki thinks the stock ones are a work of "art" :woohoo:

Kawasaki isn't the only manufacturer that uses ART pistons. D*mn good product in my opinion.
I've had a many a good time rolling with ART pistons. They work, period. Are they the best? For their intended purpose, probably so. For hammering on relentlessly, probably not. :whistle:

650ed wrote:

Powerstroke_fan wrote: Ya they sound like they are stock. I believe my stock pistons said ART on them.

Stock KZ650 piston:

Attachment PISTON.JPG not found

Damn Ed even your pistons are shiny :silly:

Thanks guys for the response. Haven't had the time to do any measurements. I can see the bores have been honed by one of the P.O.'s. and look like they haven't many miles on them since. And visually the pistons look good. I'm hoping I can just replace the broken front cam guide that I went in there for and slap it back together without having to do anything else. Just too much going on right now.

The reason I was asking if the pistons are OEM or not was to determine if the displacement has been punched out or not.

KZJOE900 wrote: The reason I was asking if the pistons are OEM or not was to determine if the displacement has been punched out or not.

Could be KZ1000 oem pistons, which would make it "punched out"

BlackZ1R wrote:

OldSchoolZ wrote: Yep, Kawasaki thinks the stock ones are a work of "art" :woohoo:

Kawasaki isn't the only manufacturer that uses ART pistons. D*mn good product in my opinion.
I've had a many a good time rolling with ART pistons. They work, period. Are they the best? For their intended purpose, probably so. For hammering on relentlessly, probably not. :whistle:

Sorry should have inserted "sarcasm" note. I wrenched at dealerships for 20 years, and have seen one or two pistons in my day.

OldSchoolZ wrote:

BlackZ1R wrote:

OldSchoolZ wrote: Yep, Kawasaki thinks the stock ones are a work of "art" :woohoo:

Kawasaki isn't the only manufacturer that uses ART pistons. D*mn good product in my opinion.
I've had a many a good time rolling with ART pistons. They work, period. Are they the best? For their intended purpose, probably so. For hammering on relentlessly, probably not. :whistle:

Sorry should have inserted "sarcasm" note. I wrenched at dealerships for 20 years, and have seen one or two pistons in my day.

yup, good times

By the way, I dig your Z1R