Archive of BMW Motorrad Club Cape (2006 - 2019)

The ignition wiring on older bikes (where the ignition switch is on the handlebar) eventually perishes and breaks due to the continual flexing as you turn the handlebars.

Symptoms

• Bike stutters occasionally, randomly.  This may seem random but is caused by the steering being in that one tiny position where the wires no longer make contact.
• Bike cuts out when you turn the handlebars left or right.
• Eventually, the bike will only run when the ignition wire is held in a certain position.

Fixing Options

In the field

• Cable-tie the wire from the bottom of the ignition switch into a position where the wires make contact again.
• Jam a stick or other item in such a way that the wire makes contact again (I did this once).
• Cut the wire and twist the relevant wires together to emulate the switch "on" position.  This requires you to know which wires need to be connected, and which not.  And a mistake here could fry your loom or break things (especially on modern can-bus bikes).

On the 1150 GS, the wiring looks like this:

Underside of ignition switch

This is one place where failure occurs - the solder joints become brittle and lose contact.  The heatshrink on the purple wire covers a past repair.

On an 1150GS if you had to "hotwire" the bike, you would twist together the red and green wires, and the grey and grey-blue wires.  Keep them separate from each other and don't allow them to touch the frame (insulation tape is your friend here).

In the workshop

• Re-solder dry joins in the switch
• Test each wire with a continuity tester.  The wires corrode inside and break inside the insulation.  By the time you have finished re-soldering, chances are the extra flexing has caused other wires to break, so test again.
• If you are handy with a small brass tube and can get the connections out of the plastic connector, you might consider replacing all the wires between the plug into the bike and the ignition switch.
  Plug into the bike loom from the ignition switch
• Or, replace the whole part - price about R1400
• Or, you could wire a DPST switch to switch between "On" and "Off" and mount it on the frame near the steering bearing.  Then your ignition key would only be for locking the steering, and you could just switch the bike on or off with a simple switch.
• Or, mount an aftermarked ignition switch with key/smartchip/bluetooth on the frame.