In a ring type engine you can buy separate piston ring and sleeve, in an abc type piston and sleeve came ( and will be trashed ) toghether I suppose that the tollerances are much more tight in abc and every piston must be matched to its sleeve. How these matching is made? by hand or there is a machine?, in a used sleeve can be fitted a new piston?

Ampa- The term 'abc' means aluminum brass chrome plated. Aluminum piston, and brass liner that is chrome plated.

ABN refers to sleeves that are nickel plated.

AAC means the process that Saito uses for aluminum piston, aluminum cylinder (no sleeve), and is chrome plated.

You can have abc ringed engines. The difference between ringed abc and nonringed abc engines is the pinch in the sleeve for nonringed engines. The top is slightly smaller in diameter. This pinch gives the cylinder compression at the top of its stroke. Most two stroke engines are ABC and nonringed.

A Kange is both ringed and with a pinch.

Go to this link how the ABC sleeve/piston are made in post #22 : http://www.rcuniverse.com/forum/fb.asp?m=6281801