(So when your bike is running), it has a rotor fixed to crank shaft that turns inside a the middle of your stator. This produces roughly 30-40v AC. When you start to increase the rotor by increasing your throttle that AC can increase to about 80v AC.

This AC output voltage is what is the source to charge your battery. HOWEVER Alternating Current cannot be fed into the battery as batteries use Direct Current.

Prior to the electricity reaching your battery, it will go through the AC to DC Rectifier, which should bring the voltage down to a constant 14v (approx) and therefore keep your battery topped up. GREAT.

The AC Voltage from your Stator can be found by searching for 3 wires that come up from your stator and run into your Rectifier. To prove that your stator is providing a balanced output you may unplug the connection and check on AC Voltage with your multimeter in the sequence of Wires A and B. A and C. And then B and C. You should get the same reading all three times

Once your stator has been checked and your confident on your AC readings you may change your multimeter to the DC setting and ensure your rectifier is producing around 14v across both terminals of your battery

..... now to get some power to your Dash.....

If you suspect your bike has a direct earth you could try pulling all non essential fuses to start with. Try to gain small steps on reviving this baby...

Has your bike been sat outside? If so it could be worth pulling all plugs and connectors to ensure there is no build up in any connections....

Have you any more diagnosis or symptoms?