You are missing the point. Nothing has to be grounded if that's what you want to do. The only system that MUST have a ground is an estart bike because of the starter motor. An estart bike must have battery minus tied to ground in order to power the starting motor.
Since you haven't said your machine has estart, I have given you information regarding a regular kickstart bike. All lighting is grounded and you only use voltage regulation. A stock estart machine is different. It has both sides of the system grounded based on halfwave rectification.
As soon as you use an aftermarket fullwave rectifier, you MUST take grounding into account.
If you want to keep your AC lighting grounded, then any fullwave DC you create must be floating (isolated). In this case your battery has no ground connection. The r/r output is not grounded and your DC lighting is not grounded.
If you want to ground your DC voltage, then the stator ground has to be lifted. This means your AC lighting has to be ungrounded. It can only connect to the stator yellow plus the lifted wire. So now your AC voltage is totally separate from the engine and frame. All load wires that were previous grounded must be disconnected from the frame and attached to the lifted wire. This means every connection point. Any wire that is not modified will result in problems. Since this is more work, everyone will recommend that you float (isolate) the DC power.
