William,

You seem to be talking about four-stroke engines, yet you talk about the cylinder plating.

I saw this also come up in an OS.50SX thread.

The two-stroke, tapered-bore engines from OS are ABN, while their Sanye China clones are true ABC.
But the four-strokes from both manufacturers are endowed with a hardened steel sleeve.

It could be chromium plated and is, especially in many popular gas engines, but I don't think any of the four-strokes are even claimed to have a chrome plated sleeve. YS has a nickel plating, but it's in a more durable, Nikasil like process.

The OS.50SX has a simple steel sleeve also.

Most cast iron ringed engines are set up this way.