1996 ST1100A ABS II: Soft Rear Brake - Root Cause & Bleeding Tips on LBS, Linked Braking System

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Btw, I also adjusted the length of the master cylinder pump rod that connects to the pedal by at least a 1/4". I may have altered it when I added a foot peg lowering kit years ago.

 

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The vacuum bleeders are good at pulling the fluid into the system - but they are useless for the final bleed. The problem is, that even if you wrap PTFE tape around the threads of the bleed nipple, when you suck air through the nipple with a vaccuum pump, it is easier for it to pull air past the thread and back up the hole in the centre than it is to pull the fluid through the system - even with PTFE tape on. So you get a constant stream of tiny bubbles.

I respectfully disagree. I have used vacuum bleeding since the 1990's on my cars and bikes and never finished up with a spongy pedal. And yes, I used it on my 1300 too. Sure, the vac pump I use does pull a constant stream of tiny bubbles, but it also sucks brake fluid through the nipple (or speed bleeder) when the sb is loosened. In fact, after I put speed bleeders on my VStrom I had very few bubbles in the line because that brand of bleed nipple comes with a pipe dope coating (they sell a small bottle of their preferred pipe dope, too).

I started out using a Mitey Vac that very quickly gave up the ghost and I think I only used it on one of my Moto Guzzis. Mitey Vac nicely made my model obsolete and I replaced it with a Robinaire vacuum pump (used for a/c work) after I got into veneering. I have a T with a valve so I can adjust how hard (or soft) a vacuum I want to pull . Brake fluid goes into an old 2 1/2 gallon galvanized gas can after I dropped my glass mason jar reservoir.