Rev and speedo needles going up and down

[Disorderlypunk]

forget ecu that doesnt control your other electrics just engine timing really


your most likely facing a bad earth - had a similar problem on my old honda BROS just cleaned battery terminals on mine but likely to something else
- but what do you mean by battery main switch ?? if you mean like an isolator switch that kills the battery feed then i would definatly start with that
especially as you said you turned it off then on again and it was fine