what's the best way to flush a master cylinder and line?

[ballvo]

The hydraulic clutch on my Concourse failed on me last night and I had to trailer the bike home. Opened up the master this morning and the fluid may be a bit low but more concerning to me is the fact the fluid is dark in color and there's black residue in the reservoir. It has a SS line (upper portion anyway) but obviously hasn't been opened or looked at in many moons.

Any way to flush and clean the system with it in place on the bike?? I'm a little reluctant to just drain through the lower end of the brake line for fear of some of the crud plugging things up internally.

Thanks,
Neil

[Deleted]

Denatured Alcohol is what to use, tear it down to do it properly is best.

[Curtis]

Sept 30, 2015 17:33:38 GMT -5 @bikerdon said:

Denatured Alcohol is what to use, tear it down to do it properly.

Plus 1 on that...

[ballvo]

Thanks, guys.

Would you just run the alcohol through the system to flush it? then recharge with DOT4 and bleed as usual?

Last night I sucked all the filthy fluid out of the reservoir with a syringe, then cleaned the reservoir with brake cleaner before filling with clean fluid. Then I went at it with my MityVac attached to the bleeder, sucking copious volumes of progressively cleaner fluid through the system. I did manage to suck the reservoir dry a couple of times. Eventually there was only clean DOT4 coming out the bottom and I proceeded to bleed the system in the normal way until there was no sign of air bubbles.

Buttoned it all up and voila .... still no clutch disengagement . It was late by then and I had to rack out.

Looks like the slave cylinder may need a bit more attention...