Master Cylinder rebuild procedure?

I've done it on cars before, but am a little stumped on my 1982 Gpz 550 rear. I thought when I took the circlip off I would have access but either something is rusted fairly solid, right now it has been given a good PB Blaster spray, or I'm not understanding how to do it.Whatever is on the output end, of the “piston” seems to be completely gone or disconnected.I hate to mess with whatever is on input side since I don't understand it and may damage whatever is going on there.It also may be that it doesn't matter, I may need a new/replacement. It appears Z1 Enterprizes may have one for it, but I'm not sure. If anybody knows where a new or substitute one is I'm all ears. Since I saved a ton of money by buying Chinese slide diaphragms, I can use the money saved to buy a new rear MC (LOL)

Once the circlip is out the plunger should pull out...unless corrosion is holding it in.  If that's the case you are on the right track by soaking in PB Blaster.  Some heat won't hurt either.  You can try to compress the plunger then pull back on it hard using vice grips or similar.  The idea being to shock it loose.  Once you get the plunger out inspect the bore carefully.  If there is pitting (quite likely) the master is junk and can't be rebuilt without sleeving (which is expensive.)

here is a pic of it, as you can see on the circlip, there is quite a bit of rust
I'm thinking given all the rust I can see, I'm probably going to need a new MC, it says 14 on the outside which I assume is the bore diameter, all the MC Z1 Enterprizes show are 12.7mm
so I'm thinking I'm going to have to look elsewhere

No eBay APP ID and/or Cert ID defined in Kunena configuration

wrote:

here is a pic of it, as you can see on the circlip, there is quite a bit of rust
I'm thinking given all the rust I can see, I'm probably going to need a new MC, it says 14 on the outside which I assume is the bore diameter, all the MC Z1 Enterprizes show are 12.7mm
so I'm thinking I'm going to have to look elsewhere

Here you can buy your MC piston assy 43020-1019

www.cmsnl.com/kawasaki-kz550h1-gpz-1982-...ston-assy_430201019/

www.partzilla.com/product/kawasaki/43020-1019



fits following models

KZ1000J1 (1000cc)(81)
KZ1000J2 (1000cc)(82)
KZ1000K (1000cc)(81/82)
KZ1000M (1000cc)(81/82)
KZ1000P (1000cc)(82/83/84/85/86/87/88/89/90/91/92/93/94/95/96/97/98/99)
KZ1000P (1000cc)(82/83/84/85/86/87/88/89/90/91/92/93/94/95/96/97/98/99)
KZ1000R1 (1000cc)(82)
KZ1100A (1100cc)(81/82/83/84/85)
KZ1100A (1100cc)(81/82/83/84/85)
KZ1100B1 (1100cc)(81)
KZ1100B2 (1100cc)(82)
KZ1100D (1100cc)(82/83)
KZ550H (550cc)(82/83)
KZ550H (550cc)(82/83)
KZ750E (750cc)(80/81/82)
KZ750E (750cc)(80/81/82)
KZ750E (750cc)(80/81/82)
KZ750H (750cc)(80/81/82/83)
KZ750N (750cc)(82/83)
KZ750R (750cc)(82)

 

It looks like I need a new MC, ideas of where to get one, or which generic one to get and adapt to my bike?

What does the bore look like?

Wish I knew, I cannot even get the thing apart, it is rusted so bad.

I've been soaking it for days in PB Blaster, applied heat (a propane torch), hammered on it, if I put any more force on it than I have been, it will probably destruct.
I suppose I should try and if it breaks, it breaks, it is junk to me the way it is now anyway.

wrote:

Wish I knew, I cannot even get the thing apart, it is rusted so bad.

I've been soaking it for days in PB Blaster, applied heat (a propane torch), hammered on it, if I put any more force on it than I have been, it will probably destruct.
I suppose I should try and if it breaks, it breaks, it is junk to me the way it is now anyway.

True. Try compressed air. Cap the reservoir nipple and apply air into the banjo bolt area. 

I have found its much easier to replace old master cylinders with newer used units. If you search around on Ebay you can get an idea of what is available in 14mm - I believe for that size I found one from a Vulcan that worked great. Stick with the size your replacing.
This way its easier to obtain rebuild kits and it will probably have a lot of life left in it. If that used master came off a running bike it probably will not need a rebuild, the one I got did not but its not 100% guaranteed since your dealing with used parts. I like to stick with used Kawasaki than new Chinese.

compressed air might work but I found another solution I thought I would share in case anybody else runs into the same problem:

I used the threaded rod to twist/pull the "puck" out. I did it by placing several washers I had in my misc hardware drawer left over from building a deck, then place the original nut over them. The washers had an ID big enough to fit on the threaded rod and big enough to fit over the MC body at the bore opening. Then I tightened the nut down, I'm not sure if it was rotation or the force of pulling the rod out by turning the nut down(maybe both). Oh, and I had given it a bath of PB Blaster over the space of a week.

My initial inspection shows the rust was limited to the "puck" area it appears the bore is not pitted, although I am soaking it in PB Blaster and will know in a couple days if it is suitable to reuse.
If not, I guess I'll be looking for a used MC. It looks like a lot of Kawi 750's, 1000's, and 1100's from 1980 to 1983 used this MC, and also, it appears the 84-86 ZX550 also used the same MC body, in fact it appears the same everything except remote reservoir and the hardware that attaches the MC threaded rod to the brake pedal.
I'm pretty sure I can find one and avoid trying to adapt a different one.

Cool idea. Great you have options.