Just been back to Halfrauds. My bike is a 1999 and according to their list needs a YB16AL-A2. Which was £4 cheaper In total, £40 using a trade card, which is the same price as it is online today. I've assembled the battery and put it on charge. Tomorrow I can start it.
I had a VARTA YB16AL-A2 battery on my 916 on an Optimiser for around 3 months while i was working away, put the key in to start the bike without unplugging the charger and the battery exploded with liquid al over the place, haven't fitted a new battery yet, cant remember reading that you shouldn't do that but certainly wont do that again.
What you should do asap is wash the affected areas of the bike, mainly the engine I would think, with a strong bicarbonate of soda solution to neutralise the acid and prevent corrosion or in a few months the alloy will be all white and furry and any steel bits with will be very rusty.
