Greetings Apolis61+,
Congratulations on your "new" BMW R60/5!
As a new to you motorcycle....A BASE LINE, service is in order. This will help you to have a Reliable motorcycle.
The /5 series are very similar to the later /6 and /7 series....Also, the later series of airheads...without the / designation, airheads.
Online, you will find Tremendous and Detailed information. SEARCH.
Regarding your recent, Electrical troubles...Perhaps, the battery is a good one. Give the battery a FULL CHARGE.
Now, Disconnect the Negative cable. NOTE> The Factory negative connection, is at a SPECIAL HOLLOW BOLT, at the gearbox. This special hollow bolt, allows the gearbox to VENT. Secondly, this Ground Connection, can be STRIPPED very easily, as the steel bolt threads into Soft Aluminum. Some, will connect the ground to a transmission mount bolt.
With the GROUND Disconnected...Remove the fuel tank.
Now, disconnect each and every electrical connection....ONE at a time. Clean and then "grease", each connector. Conductive Grease, is a good idea.
Included here, is Part of the Ignition System. The Coils and the Spark plugs. IF, one spark plug is Tight, try removal, after a ride, when HOT. A few drops of light oil at spark plug threads, helps.
There, you have completed, MUCH...of a Baseline Electrical Connector, service. There is much more, within each lamp assembly, the
headlight bucket, starter motor and its bendix (big solenoid), and Under the Front Engine Cover, where the Charging and Ignition, systems are located.
NOTE> BEFORE removal of the Front Engine Cover> DISCONNECT THE NEGATIVE GROUND CONNECTION! EVERY SINGLE TIME!
I LOVE my /5!
Ask questions. Search, online first.
HAVE FUN!