Kawasaki Sportsbike Riders Club - Australia - Online Forum

Hi guys, rode back from work last week 06 Zx10r, 4hrs bumpy roads no problems, hopped on yesterday and almost zero front brakes even after pumping them. Tried bleeding them this morning, I have brembo P4s on the front, braided lines, and standard master. Would not firm up at all. I even tried using a syringe lever out and depressed and was sucking hundreds of air bubbles and little fluid. Re-checked for loose connections etc and can't see anything. I am thinking master cylinder, how can I narrow this down? Or any other suggestions?
Any help will greatly appreciated, I am thinking a brembo master would look awful pretty but $ as always are a bit tight

You could strip the master cyl down and have a look at the bore and the seals. Any pitting/corrosion (electrolysis) of the bore can damage the seals which then allows fluid to bypass the seals into the reservoir or air to suck past the seal. Shiny polished sections indicate wear in one area allowing bypassing also.

Brake fluid is hygroscopic so it absorbs moisture from the atmosphere. A nice way to see this affect put a small becker/shot glass on a saucer and fill it till it nearly overflows, then leave it out overnight. Next morning it will have overflowed into the saucer from the water it absorbs.

Before you attempt striping you could try cracking all the bleed nipples at the same time on the front calipers (with bleed lines attached for each) and gravity bleed the system. This requires no pumping(may require an initial squeeze but that's it) but with gravity bleed you have to keep topping the master.

I live in Kippa ring so I'm happy to have a look if you like.

Thanks heaps for the reply, I'll try the gravity bleed and let you no how that goes before stripping, cheers for the offer of help

I had the same problem trying to bleed the r1 mc/callipers...
the only way I got them good was from a vacuum bleed ,if you have a compressor and vacuum bleeder you will end the prob's imo.

Had another go this morning and got them to firm up, will have to see if they fade over the next few days and the master is perhaps leaking. Thanks for the help