Expect the new rings let more blow by pass by them.
New piston rings are not perfectly round. New or used cylinders are not perfectly round either. New cylinders are given a final honing after the Nikasil plating has been done.
This leaves a crosshatch pattern in the cylinder which has 2 purposes. It holds oil in the valleys of the hone marks to give additional lubrication during break-in and the peaks of the hone marks acts like a file and wear the rings in for a perfect seal, well as perfect of a seal as one can hope for.
After the cylinder has a few hundred miles on it the crosshatch has been worn much smoother. The valleys are shallower and the peaks are dull.
When a cylinder is new the crosshatch in the cylinder is sharp.This is why a good break in is necessary. It allows the rings to marry (conform) with the cylinder quickly.
Unfortunately Nikasil plated cylinders cannot be re-honed to provide a fresh crosshatch.
The plating is only a couple thousands of an inch thick and re-honing would wear through it completely or make it sooo thin that the rings would quickly wear through it and the cylinder is junk in a short time.
The new rings will eventually marry (conform) to your used cylinder but it will take alot longer than when the cylinder was new, thus the increased blow by.
