Originally Posted by BillyT
You just have to keep bleeding it. The line is fine. If the pistons aren't all the way out it is going to take a long long time.
These masters move such a tiny amount of fluid at a time, and even less air.
Just keep going. It's gonna take what seems like forever, but it will eventually bleed out. And forget the vacuum bleeder. All that is gonna do is suck all the fluid out of the caliper. Never had luck with those on HD brakes. Work great on the jap brakes that are on my bike now, though...
I've never bled brakes before until today and I have to agree with what's written above. I did my front brake and it took me about 4 hours and it will never take me that long again now that i've done it once. Most of my time was wasted trying stupid little tricks and fucking with a vacuum bleeder. What ended up working for me was pumping the brake handle a bunch with the bleeder valve closed... probably like 15-20 times. After doing that I would squeeze the lever in and HOLD IT, crack the bleeder open real quick, watch some bubbles and fluid come out into the tube, close the valve THEN LET GO of the brake lever. After repeating this a bunch of times I finally had front brakes again. One thing that helped me to initially get fluid running down into my new hose (which for the first hour never happend) was to prime the master cylinder by taking the brake lever off and pouring some brake fluid directly into the cylinder then screwing in the banjo bolt and fitting. It was a little bit messy but before doing this my master cylinder would not draw even a single drop of fluid from the reservoir. It sucked wasting so much time screwing with it but now that i got a feel for bleeding these HD brakes I'm sure it'll come a lot easier next time.