(Note: this applies to all R1200 LC and R1250 BMWs.)
Hi again, all!
There are a number of reasons why it can happen (bike previously worked on by someone who knew enough to get themselves into trouble, is the usual culprit), but once in a blue moon, you may get the front or rear brake lever going as soft as two-week-old celery (and to the end of its travel) with the relevant brake kicking in very late, if at all.
If this happens:
This procedure can't be done without using a diagnostic tool of your choice. In my case, I use a Hex GS-911 (Detected Vehicle > ABS Brakes > ABS Functions > Bleed Brakes).
The procedure lets you do a fluid-in-at-reservoir-and-out-through-nipple bleed. It works by using the bike's own ABS pump to pressurise the brake circuits while opening and closing the ABS pump's pressure relief valves.
The GS-911 interface is user-friendly, and guides you through the procedure.
If you're specifically purging a stubborn air bubble, I've noticed a need to modify the procedure. Instead of following the bleed instructions to the letter, repeat the 'power bleed' ('Brake Bleed 1' on the GS-911 UI while depressing the brake lever, 'Brake Bleed 2' while doing the same, ignition off, ignition on) as many times as needed without bleeding any fluid, until you feel full brake pressure at the relevant lever. Then, and only then, do the bleed procedure according to the instructions on the GS-911 UI.
Continue bleeding until you see no air bubbles whatsoever in the waste fluid.
Be aware that ABS pumps are power hogs. It's always best to do power bleeds with an intelligent charger (preferably one with some kind of 'boost' function) connected direct to the battery poles. I use a Ctek MXS 5.0, set to the 'car' setting.
Hi again, all!
There are a number of reasons why it can happen (bike previously worked on by someone who knew enough to get themselves into trouble, is the usual culprit), but once in a blue moon, you may get the front or rear brake lever going as soft as two-week-old celery (and to the end of its travel) with the relevant brake kicking in very late, if at all.
If this happens:
- Don't panic. See step 2.
- Know that it's more likely to be an air bubble in the braking system than it is to be a compromised line, a loose fitting, a bad seal, or any other nasty.
- Know that if it is an air bubble, manual bleeding almost certainly won't shift it, no matter how much fluid you put through the system. This applies to 'conventional' bleeding (pour fluid into reservoir, bleed from caliper nipple) and 'reverse' bleeding (use syringe to force fluid through caliper nipple, draw excess fluid from reservoir).
- Know that 'power bleeding' the brake circuits on K5x is the procedure approved by BMW, and should be used every time the brakes are bled.
This procedure can't be done without using a diagnostic tool of your choice. In my case, I use a Hex GS-911 (Detected Vehicle > ABS Brakes > ABS Functions > Bleed Brakes).
The procedure lets you do a fluid-in-at-reservoir-and-out-through-nipple bleed. It works by using the bike's own ABS pump to pressurise the brake circuits while opening and closing the ABS pump's pressure relief valves.
The GS-911 interface is user-friendly, and guides you through the procedure.
If you're specifically purging a stubborn air bubble, I've noticed a need to modify the procedure. Instead of following the bleed instructions to the letter, repeat the 'power bleed' ('Brake Bleed 1' on the GS-911 UI while depressing the brake lever, 'Brake Bleed 2' while doing the same, ignition off, ignition on) as many times as needed without bleeding any fluid, until you feel full brake pressure at the relevant lever. Then, and only then, do the bleed procedure according to the instructions on the GS-911 UI.
Continue bleeding until you see no air bubbles whatsoever in the waste fluid.
Be aware that ABS pumps are power hogs. It's always best to do power bleeds with an intelligent charger (preferably one with some kind of 'boost' function) connected direct to the battery poles. I use a Ctek MXS 5.0, set to the 'car' setting.
