This isn’t a how-to. Just something I’m working on at the shop.
I was commissioned to split the right tank of an aftermarket set of stretched flat-side tanks so that the front of the tank would hold oil. Years ago…a long time ago… quite a few companies used this type of setup on there factory bikes.
You want to start by deciding your cut lines. I knew what volume of oil the customer wanted and worked back from that.
Since all the bung fittings will be located on the bottom of the oil tank I ran internal lines for the vent and return.
Back together…ready for body-work and paint.