KZ900 stock cylinder block bore?

I'm having a problem trying to determine what size piston rings I need to order for my stock 900 engine.
My engine, number Z1E11511, is stock but the cylinder is stamped with the number "2" in front of each piston sleeve. I'm assuming this means the cylinder was over bored at the factory.
I see on some web sites that they sell over size rings but I'm not sure what the number "2" represents?
The other issue I'm running into is that all of the sites that have stock pistons rings say that the oil ring is a three piece ring. My oil ring is a one piece ring???

I'm hoping someone out there can shed some light on this??

Thanks,
Buzz

It should be a 3 piece.
If possible post a picture of the piston, rings, and the cylinder block.

Here are the pictures of the block, piston and ring set and the oil ring by itself.

Hope this helps

Looks like I'm having technical difficulities... here's the block.

A closer look at the block!

And the piston and the three ring set...

The easiest way to determine is the following...

Go to Harbor Freight Tools, Home Depot, ACE hardware, Lowes etc... and purchase a digital caliper... ~ $20-$30...

I promise, you will use this tool more times then you can even think of in these retro fits/modifications of these old beauties...

Measure the diameter of the piston. You can even measure your inner ring dimensions this way as well as the cylinder bores. Then you will know exactly what you have in pistons and ring sizes.

If I remember correctly, stock kz900 pistons were 66mm.
They measure 65mm at the crown and 65.9 at the bottom of the skirt.

OMR

Hey KruZer; I gonna go out on a limb here and say that the "2" stamped in the aluminum on the deck references the size of the bores. I seem to remember reading something about "when fitting new factory pistons, look to see what number is stamped on the cylinder block" I can't give you specifics but just a general idea. When the factory finishes the honing, the bore size doesn't always come out to nominal dimension and they use the number code to tell the assembly people which pistons to use (whose diameters also don't always meet nominal. It's the same with most other critical engine components like crank bearing journals and gears. Hope this helps you in some way and it may jog the memory of others for the specifics. The bottom line is what the bores measure now and what the ring gap will be. Ride safe, Steve

measure your piston and bore and make sure u dont need larger pistons befor u worry about the rings. if u need rings call Dawn at Hastings rings.com. she can supply all dif types and sizes.she will need the bore size and ring thickness.

The cylinders (sleeves) and pistons are well within specifications so all I really need to do is find out where I can buy the correct set of rings.
I've called a few parts vendors and none them have heard of a one piece oil ring for the KZ900.
I guess I could just buy a used set of 1000 pistons and bore out my block but I hate to spend the extra money on the pistons and boring...... and still have to purchase a set of rings for the 1000 pistons...

Thanks for all the advise...

Buzz

Those are Stock pistons and rings. Stock pistons are by ART
Check Z1 Enterprizes.

does it look like the top of cylinder has been decked/milled ?might of been there way of marking if cylinder was warped at one time