Stud Assembly
Contains seats, guides and rocker shaft bushings (if applicable).  Cylinder bore is either standard or oversized steel, chromed.  The cylinder is painted and ready for assembly.

Valve Assembly
Same as a stud assembly but with valves, springs and spring retainers installed.

Complete Assembly
Same as a valve assembly but with piston, piston rings and piston pin installed.
Rings are gapped and positioned.

Choke
The reduction in diameter of the cylinder barrel at the head end at ambient temperatures. The heat of the combustion allows the barrel to expand more at the head end than at the bottom causing the barrel to be virtually straight during normal engine operating temperatures.