Leaderboard

I'll have a look this weekend! What gauge wire should I use when running the ground wire off the regulator?

I looked back through the entire thread and have to suggest adding a dedicated ground/earth from the regulator case to the timing chest. Also, to clean/tighten/seal the main ground to the back of the gearbox on the right (behind the seat latch actuator). It would be telling if the charging voltage changes after addressing the grounds.

Before you do that, make sure the headlight is working. In the headlight there are two bulbs, one standard low beam / high beam headlight bulb and one running light bulb. It is easy to mistake the running light bulb being on for the headlight working. If the headlight bulb isn't working the regulator won't properly charge the battery. Because it uses the voltage on the headlight circuit after the headlight bulb to measure battery voltage. The bulb can be burnt out or the circuit might be off (blown fuse or faulty relay). You may need a new regulator, but make sure before going that way.