Alright... here goes.
'97 Monster 750. Dual front brake conversion (done by previous owner) using a junction block bolted to upper triple (looks stock from a 900 maybe?).
After changing over to clip-ons I bled my brakes and have been having some trouble ever since (actually I've now bled them three times, LOL).
Brake lever takes a long time to "pump-up" while bleeding. As in I bleed, then the lever travel is long and after about 20 strokes it comes back to where it should be. I've bled it manually (squeeze lever, open bleeder, close bleeder release lever). I've back bled it (forcing fluid from the caliper up) and I've used a vacula (sucker) to bleed from the caliper down. I've done it with the brake lever pulled in and out. One would think I've gotten all the air out.
They symptoms: Brake lever pull is randomly different. I'll leave the house in the morning and have a great lever all the way to work. Then I leave for a ride after work and get a lever that's slightly closer to the bars under full stop. Then I'll run a good pace through the hills and pull to a stop light to get a lever that barely takes any pull to apply brakes. The lever never really feels squishy and once it contacts it doesn't get closer to the bar (like fluid bypassing in the master).
The bike has new pads and upon installation I inspected the calipers. Everything is clean and working smoothly.
So what gives. I feel like there's still air in the lines, but I can't imagine how. I've bled it every possible direction. I've got a track day next weekend and want to make sure that I don't end up with a master cylinder failure. How long do the coffin masters last? Is this a common failure, or does it sound like I'm on the wrong track?
Thanks in advance guys. I appreciate any input or wisdom.