Nice professional iron sleeved KX 80 cylinder. Doesn’t look to have been ported, but it’s a big bore cylinder. Presuming this was a 51.50mm bore to start with , and currently is 51.622, that puts it at 95.4cc at present. Next size up (51.75mm) makes it a potent 96.33cc. Sadly this bike came without a piston so I can’t cross reference you a piston, but I see Wiseco offers lots of 51.75mm two stroke pistons.

Anyways, good overall condition but it should get bored to next size. Easy though with iron!