I'll take a stab at it when I'm back in town and can get to it.

My brakes were seizing up again so I drained the master cylinder and sure enough you could see some crap in there. I cleaned it out again and went poking around and trying to put tiny wire into the ports it wasn't opening up. I got some canned air and gave it a hit with that. Blowing on a tube back through where the banjo bolt gave me some flow through. A quick bleed and good to go.

Well it's running pretty well. I know my carb rebuild wasn't perfect but it's ok. Still fun to run around on. Out the other day for what might be the last half warm day of the season. 

Posted by: @16813

↑

My brakes were seizing up again so I drained the master cylinder and sure enough you could see some crap in there. I cleaned it out again and went poking around and trying to put tiny wire into the ports it wasn't opening up. I got some canned air and gave it a hit with that. Blowing on a tube back through where the banjo bolt gave me some flow through. A quick bleed and good to go.

Yes, the max life on DOT4 brake fluid is 5 years, or crud starts to appear. This is why BMW recommends replacing your DOT4 every year. A lot of owners skip this necessary maintenance because 1) it's a pain, and 2) DOT4 is corrosive and an easy way to spoil a nice paint job. 

Owing to the way BMW brake hoses are routed, they can trap a lot of air. I always had better luck pushing new fluid in from the caliper end. But we all use the tools we have.

► Due to the highly corrosive nature of the fluid, I really recommend dousing the entire bike in HOT soapy water to make sure all the DOT4 got removed.

► Just for your personal education, here's some suggested reading...

https://www.airheads.org/community/parts-is-parts/brake-hose-failure-causes-cures/#post-6217

Hope this helps.

Thanks Richard. I'm sure the old fluid had been in there for many years.