I first had to purchase a caliper to measure the bore of the cylinders. Believe it or not, I am not in the habit of needing to measure the diameter of engine cylinders... Harbor freight sells a nice little digital caliper for 20 bucks. Cheap!
I had to run a hone through the cylinders to remove rust that might interfere with the measurement. I actually still have the hone from when I rebuilt the 454 Corvette motor. In the years since I honed the big block Corvette engine, they have invented and perfected cordless drills - a sweet match!
According to the caliper, my spare cylinders are 60 millimeters across, or standard bore. Pretty sweet... until I looked down them after honing and saw aluminum melted inside the center cylinder liner. I guess that's why the cylinders came as "spares" with the drag bike. OK so they need to be bored also, but since they are standard bore, they should have more metal left than the current set.
The bits of melted piston were my first clue the center cylinder might have... issues. And this is AFTER light honing.
A look further down reveals some nastiness. This should be removable with an overbore.