HELP! rear m/c will not come apart/83 kz750spectre

83 kz750 spectre...
it was someone's yard art for years.. working on a total re build.

i have read and re-read the manual. the rear system is completely apart and amost ready for cleaning and new parts, but i cannot get the dust cover out to remove the piston. the retaining spring (kinda "C" shaped bugger) has been removed and the the piston travels through the obstructing piece. the maual shows it as a dust cover, but i have already removed the soft rubber job that covers everything. this piece appears to be metal and corroded. i dont want to break it as a replacement is not in my rebiuld kit. the fill port was difficult to remove after removing the retaining ring and was filled with powdery aluminum rust... i am hoping a little force will pop the bad boy out, but want to consult the wise minds here first.

thx you for your time..

One thing at a time. You have the rubber boot off, and that 'the piston travels through the obstructing piece'.

Now remove the piston too, use an automotive rifle-crank-style grease gun if you have to in order to force the piston out.

THEN with the rubber boot off, and the piston out,
*maybe* the remaining part will come off quite easily.

I don't have your model but that's the way I always approach stuff.

First -- do everything I can.

Second -- then tackle the remaining. Very often step 1 in various ways makes step 2 a breeze.

I have the exact same problem with the rear m/c on my 550 GPz. The piston will not come out until the piston stop is removed from the bottom end of the m/c body. The retaining spring is out, but the piston stop plate is rusted and won't come out. The piston won't come out till the piston stop is out. I have looked in vain for a NOS rear m/c. Does any body have any experience getting the m/c apart, or does anybody know where I can get a NOS or good used m/c for my 550 GPz? I have a new piston and seals.

well i ended up finding an 82 spectre rear m/c ebay... once i tore that one apart i was able to see the large washer which retains the piston in the m/c was the problem... the old one is fused to the m/c body... it has been scrapped and the new/old one is in great condtion... the rear brakes are about ready to go back together.. the rubber in the caliper looks to be in good condition i am trying to decide if if should replace them now since i already have the system torn down...

thx you gents for all the help... the front brakes a fork seals are the last real project left... once i get that and the re-paint done i will post a biuld thread... it has been a great project soon far and this forum has been full of great information and helpful people... happy to be a memeber

I have finnaly been able to repair my '81 550 GPz rear master cylinder. I found a new piston with seals at the Kawasaki store. Looking at the new piston, I could see that if I put a Phillips screwdrive down the port where the banjo bolt goes, it would contact the top part of the piston. I put the m/c in my vice and tapped on the screwdriver until the piston stop was driven out. The piston stop is just a washer. I cleaned mine up, cleaned up the m/c body, put in the new piston assembly, and it now works! The new piston was different on the end that was contacted by the rod which the pedal pushes, but it works OK.