Forged Pistons? What is the Bore Clearance? Ring Gap?
The Nikasil Bores are probably dead-on, but Piston Diameters vary individually from the Factory.
For Cast Iron Sleeves, the Machinist will measure each new Piston Diameter and then Bore each Cylinder accordingly to proper clearance needed.
For Nikasil Cylinders, the Bore Diameter is fixed, so the only Clearance adjustment available is the Ring Gap. Or use another Piston.
Sometimes Piston Rings have an "Up" orientation. The engraved numbers on the Ring, if any, should face up.
It's worth mentioning that most, if not all, Cylinders should be washed/brushed (nylon bristles) with hot water and soap, wiped dry till no grime shows up on a white paper towel, then oil the Sleeves to prevent rust (on Cast Iron). I consider this mandatory for all Cast Iron Sleeves, and probably a good idea for new Nikasil Cylinders.
And for used Nikasil Cylinders, I understand that the cleaning process involves Muriatic Acid to remove any Aluminum/Iron Grime embedded in the Nikasil Bores, before installing a new set of Pistons and/or Rings.
