Z1-R Rear Master Cylinder - Weeping

After rebuilding the rear brake with new m/cyl piston kit, new caliper seals, pads and fitting a new hose and banjo bolts, I bled the whole system and got good pedal pressure. So, I thought "Job Done!" Not so - I noticed that the m/cyl was weeping fluid from somewhere and thought that I'd messed up the assembly. So I pulled it apart and checked/re-assembled and bled again - still weeping somewhere - damn! After wiping it all down I placed the m/cyl on the bench, filled it with fluid and observed carefully. After awhile I could see that the fluid was slowly weeping out where the plastic reservoir meets the alloy body - looks like the bond between these two parts has perished. Anyone had this before and is there any repair that can be done, or am I up for a new m/cyl? If the latter, then does anyone have a m/cyl for sale - either new or good 2nd hand?

There is an O-ring that sits between the plastic reservoir and the metal body of the master cylinder. It was never offered by Kawasaki as a replacement part, but you still may find one. The link below (see bottom of link when it comes up) shows them being offered for the front master cylinder, It's possible that one of those o-rings may fit the rear too. I would check into it. Ed

www.redlinecycle.com/Brk%20-%20Fnt%20Mas...its%20-%20Seals.html

Not specific to your question but related to the Z1R brakes.

G'day Ed - thanks for your tip. However, I don't think that the Z1-R rear m/cyl reservoir can be (easily) separated from the body, I think that it's bonded together and not designed to be pulled apart. Anyone have any more on this...? I may try carefully injecting some high strength sealant around the outer of the reservoir where it's weeping (if I can get any in there, it's pretty tight!) to see if it will seal up.

Some good news! I was able to separate the reservoir from the m/cyl body, I carefully lifted a plastic baffle plate and revealed a couple of screws securing these 2 parts. There is a seal between the reservoir and the body which requires replacement - thus the leak! Just have to source a new seal - believe that Redline Cycles may be able to help, will keep you posted. A couple of pics to help anyone else who has a Z1-R with leaking m/cyl around the junction of the reservoir and the body of the m/cyl. There's a lot of crud under the reservoir so I'll clean that out before re-assembly.

Another pic to show the internals of the m/cyl.

Glad to see it came apart ok! The pictures you posted should be really helpful to anyone else with this same or a similar reservoir. Ed

Got the o-ring from Jim at Redline Cycles and re-assembled the rear brake assembly. Bled it, good pressure at the pedal and no leaks - job done!
Front brake is next - got it apart ok. Stripped & cleaned and have new lines, seals, piston kits. Refurbished calipers, bolts etc. Just getting the h/bars rechromed and will then re-fit the whole kit and kaboodle. Will post some pics soon to help others withtheir rebuild/overhauls.

Thanks for letting us know that o-ring works! That info could come in handy. Ed