blew

HI all, I recently did a trip around the coast of Scotland, 1400 miles, for charity and during a particularly enthusiastic bit of riding I heard a bit of a pop followed by a very very loud rumble. I initially thought I had maybe blown a cylinder somehow but found I had no loss of power so...

Had my 02 Mille since new and am used to the battery appetite Bertha has. I have a shop grade wall mounted trickle charger plugged in every night just so she starts when cold. Anyway, I've has some issues starting her lately. I went to start her today and the thing almost ran before a hiss and...