Piston Ring Squaring Tool
I just wanted to share a simple ring squaring tool I added in Thingiverse for people to download and edit as needed.
I added the handle in the middle just to mark the sizes, it's not really needed. The Solidworks files are also available on Thingiverse for download should you want to change bore size or features to suit your needs.
I uploaded the 83mm for the +2mm SV650 and 80mm for stock bore FZ-07. Nothing complicated and might save you a couple of bucks vs buying one or messing around with an upside-down used piston.