How do I get to the battery in a BMW 2004 R1150R motorcycle so I can change it ?

SOURCE: Rear Brakes on my 2004 BMW R1150R motorcycle seems

Hi,
You need to remove the caliper.
Then remove the plungers, you will find that these have a type of gunge on them. Polish the plungers, clean the caliper and replace. Bleed the brakes with NEW brake fluid (the good stuff).

Cheers

Jon
NB. If the plungers are pitted then they should be replaced.