If you need to perform auto repairs on your own BMW R 850 C then it is always recommended to have a Workshop Manual to keep just for a guide just in case you want to know the right way to take out a certain component for instance the Exhaust and match it again safely.
BMW R 850 C Workshop Manuals provide you with particular diagnostic info with regards to your car or truck so if something is not working it can help you identify what the issue is and the best way to repair it. Then you are able to analyse if this can be achieved by yourself or if the job is simply too big you can still make a booking for your R 850 C into a local friendly mechanic.
BMW R 850 C manual