the big bore set was offered to me after I have asked a lot of engine reworkers to do that for me, but it was close to impossible !
The needed parts are not easy to get and the closest pistons (Ducati) still need some rework.
Find a report with some details of another modified Twin:
This shown piston has 86mm bore and gives 906 ccm. The stock sleeves needs removal, the aluminium cylinder a bigger bore and finally new sleeves. Basic information is that the wall of a sleeve must have a minimum of 2.0mm thickness.
I know two other Twins with 865 ccm, one is Martin’s from Germany and the other is ChrisLWGs from the UK 😉
Well, I can provide some more information and pics, but my engine will be completed this winter eventually, incl. new camshafts 😉
If you are looking for standard sized pistons and rings you may find it here:
PS: Gasket at cylinder bottom is paper and can be cut out with a rounded nail-scissors. Cylinder head gasket I will use is made from copper and I have an AutoCAD file for that, so it can be made by a maschine.