found piston rings for different year - will work?

so I bought a 1981 kz750 h2 block and pistons to use with my kz650 engine

problem is some of the rings on the 750 pistons were stuck to the pistons so I need to find new rings

there is a guy around here that has a few packs of 750 piston rings, but ebay lists them for a 1972-1975 h2 Mach 4 750

how can I tell if I can use these rings? some measurements I can take?

1981 h2 rings: oem 13008-5031
72-75 h2 rings: oem 13008-042

thanks in advance

Sorry, but maybe you didn't realize the 1972-75 Mach 4 is nothing at all like a KZ750. It is a 3 cylinder 2-stroke motorcycle, so no, the rings are not at all compatible with any KZ and neither is anything else on the 2-stroke 3-cylinder engines. Ed

thanks ed. just saw the 72-75 is a 3 cyl after I posted

I am scrued [sic]

if its just a carbon stick, u might try a sea foam soak, pour a container full and let em soak for a few days, blow compressed air over them, then you can remove and check ring to bore with a feeler gauge.

how easily are these pistons supposed to slide back into the barrel?

my 650 pistons slide in pretty well but these 750 pistons felt like they were way too big and I had to compress the rings all around just to get the pistons back in

that means these rings are too big or stretched?

it was an ebay find so I have no idea

Try here for piston rings:
www.hastingsmfg.com/

Do you have the Service Manual for your bike?
You need to measure the ring end gap, then be sure to clean the groove/ ring lands on the piston, so the rings fit properly. Also you need to check piston skirt diameter and cylinder bore for size so you know the clearance. Honing the cylinders, checking fit, etc. New piston rings are available for most of the KZ bikes, sometimes being NLA from Kawasaki. But there are aftermarket companies that have the rings. Try z1enterprises.com and see if they have your rings. They would have all the gaskets, a Top End Gasket Set.
Have you looked at your cylinder head? It more than likely needs some work also, a good Motorcycle Machine shop will give you an estimate.

so as per the manual the bore on a kz750 is 66.0mm

same as the kz900

so does that mean I can use any rings from a kz750, kz900 66.0mm pistons?

is there a difference in piston/cylinder clearance?

(anyone know the kz750 and kz900 bore clearance?) couldn't find it in the manual

Thanks

marla_do wrote: ...anyone know the kz750 and kz900 bore clearance?....

FSM for Z1~KZ900 says standard Piston/Cylinder clearance is .0025~.003 in. (.060~.079 mm)

Lots of good info on kawasaki.com, including parts diagrams, part names, part numbers, models sharing same part, availability, etc. Here's a link for help with navigating the site and finding information.
kzrider.com/index.php?option=com_kunena&...w&catid=13&id=376734

Good Fortune!