I feel like there is too much pedal travel before bite with the rear brake.
Insufficient improvement with bleeding, even using the inverted caliper method.
(2012 1100 Evo) Standard rear master is Part-no. 10477610: Brembo rear master cylinder PS 11B, mount spacing: 40 mm, piston diameter 11 mm.
Seems there are 12 and 13mm masters with same mount spacing and take-offs for res and brake line.
I'm getting Part-no. 10477620: Brembo rear master cylinder PS 13B, mount spacing : 40 mm, piston diameter 13 mm. Once here, fitted and bled, I'll post whether I wasted my money or not.
Insufficient or nil improvement. Still a weak brake.
I believe trying to adjust the plunger rod is only useful if there is actual slack/clearance there. If adjusted beyond the point where the master piston bottoms out, then the system doesn't bleed back, and the rear brake can lock unexpectedly. (fail to release). This can also prevent reverse bleeding.
Decided to try bleeding at the ABS unit.
Ordered bleed nipple banjos from ebay. "Single Red CNC Banjo Bolt M10 x 1.00 with Bleed Nipple Screw Valve"
They turned out to be too tall. The fuel tank does not clear their extra length. I had to settle for a rough bleed by cracking the banjo bolts just enough to allow brake fluid to come out. There was froth (air).
So far, the pedal is still weak, but at least it now works. (After leaving the bike standing for a couple of months I had come back to it only to find the rear brake non-existent.)
I have ordered different banjo bolts with bleeders that have as little extra length as possible.
Found a reference to a service bulletin for 1200 Multistrada which sounds like the same issue:
"Try the bike on the road at about 50 km/h and act only on the rear brake until the ABS has been activated at least 10 times.
Check that the stroke of the rear brake lever has not increased, otherwise repeat the bleeding procedure."
OK, did that and then bled the whole thing again, including both banjo bolts on the ABS, and on the master.
Best brake pedal since buying it. Cheesus, what a saga.
(After all that, I found this. [Haven't tried it]:
1. Ride bike till abs light goes off, then ride back to where bike will be fixed, next shut off bike with kill switch. (leaving key on with abs light out. The abs system is on and open this way)
2. Put bike on stand or jack up bike up and remove rear wheel.
3. Remove rear brake caliper and position on top of rear disc (or rear brake rotor, same thing)
4. Top off rear brake reservoir (use dot 4 fluid) and bleed rear brakes by opening bleeder valve then pushing down rear brake lever, close bleeder valve before you let the brake lever return to the up position and repeat until brake lever becomes normal again. (don't let reservoir run out of fluid)
The real key to this job is making sure the abs system is on and active as there might be air trapped in the abs unit.)
If I slowly lose my pedal again, I'll try that.