rear master cylinder

does anyone know where i can buy a new rear master cylinder for a 1977 kz650b  i am trying to get the piston out . it is stuck .. if i do get it out  i am not sure if the bore will be pitted so i was trying to locate a new master cylinder

You can buy a generic master off ebay for cheap.  After that it's typically not overly difficult to rig up a bracket of some sort to mount it to your frame.  

rlcarter post=862834does anyone know where i can buy a new rear master cylinder for a 1977 kz650b  i am trying to get the piston out . it is stuck .. if i do get it out  i am not sure if the bore will be pitted so i was trying to locate a new master cylinder

Are you sure you have a 77 KZ650 B model?

All the B models came with wire wheels and rear drum brakes. Maybe somebody retro fitted a whole new wheel/hub/brake on the back of it? The two popular mods were either a KZ1000 rear disk hub or a KZ750 Twin rear disk hub.

The C models came with rear disk brakes - Getting rebuild kits for those 14mm masters is near impossible. The size of the bore is usually cast on the body somewhere (1/2 or 14) Finding a NOS 14mm unit for a 650 is also a very rare occurrence.

If your not doing a restoration I agree with Nessism on finding a modern rear master as a substitute.

The D model came with a rear disc brake.  Manufacturing started in the summer of 77 but they are actually 78 model year.  Maybe this bike is a 78 650 SR.

I would check ebay for a MC off a 78 or 79 650 SR.

 

sorry my bad  it is a C model .. i found a used master on ebay for $ 200 sounds high to me especially if i cant find a rebuild kit for it.  might have to look for a modern one to fit
 

I have freed up some really suck pistons. Gentle heat and soak cycles. Getting the first ever so small movement is key. Once it moves just start gently working it. Patients is your friend…

 

I wonder if the parts for a front 14mm master would work? I am assuming the rear master in question is 14.

If you have access to a compressor you can usually blow the pistons out from the outlet port (put a cable tie around it or you may never find the piston  ) this is much less destructive than any mechanical efforts. If you get it out there are small honers available on EBay etc you can use to clean up the bore (they aren't expensive)

i tried air yesterday  no luck  going to soak  and heat a little today then try air again

If you get it out this might be useful to prep the cylinder bore 

thanks for the brush idea. still working on getting the piston out..  boiled it  soaked in penetrating oil put the air to it.  no luck  i wonder if i could heat it up with a torch? it may be aluminum.. not sure that would be a good idea.. 
 

If you manage to get the piston out, and you want to try to keep the stock master cylinder, here are some options.

You could get the MC repaired or sleeved by these folks:

www.applehydraulicsonline.com/collection...rake-master-cylinder

The OE kawasaki piston in not available, but the primary seal cup is here on ebay.

ebay.com/itm/OEM-Kawasaki-Primary-Cup-Master-Cylinder-H1-500-H2-750-Z1-900-KZ-43019-001-/393651356079

The secondary seal that is on the piston might be similar to the one used on the front master cylinder, even if the piston rod itself is different.  Once you get the old one out  and measure it, the folks at Brakecrafters might be able to help you find a substitute part.  They have been very helpful to many folks here.

www.brakecrafters.com/

Many of the master cylinder parts on the 78-80 KZ650 and KZ1000 were similar, but with two bore diameters based on application.  The rear MC for the KZ650C looks the same in the drawings as the KZ1000 rear MC, but it may be a different bore diameter.