I know this is asking the impossible but I don't suppose any one has a set of NOS 2nd oversize Z650 pistons and rings collecting dust ?
No? ... thought not

how about a really healthy set of barrels and pistons?
CB will be eternally grateful for a cure for her smokey little zed

see projects

Ralph Ferrand
Z1000A1 (1977), Z1300A5 (1983), Z900A4 (1976) GPZ1100 Unitrak (1983)(project), RD250B (1975)(project), ZRX1200R (2005) DT175MX (1981) YZF R6 (1999)
http://www.bikerstoolbox.co.uk