[antonye]

I've had this and it was very simple to fix - the battery connections are loose!

They may not feel loose, but if you rock the battery tray (or the reg/rec bolted underneath) you'll probably get sparks from the earth lead as the connections make/break contact.

You simply need to tighten the connections up and it disappears.

It only happens when the bike is running as the revs causes the battery tray to wobble and the sparks cause the erratic behaviour.

Mine happened when I connected the Optimate lead and obviously didn't tighten it up enough.

Hope this helps!