'81 550GPZ Rear Master Cylinder- Parts/Interchange

Hi All,
Nearly done with the brakes and ready to roll. I cannot find many of the rear master cylinder parts and no one I can find sells a rebuild kit with all the rubber bits. N/A from K&L and discontinued by Kawasaki. According to partzilla the piston is the same as the front m/c. Is there any source out the for the dust boot, piston stopper & retaining clip etc? The bores and seals have to be pretty common...

Alternatively is there a stock looking interchange of the entire unit?

TIA,Bill

Check with any Kawasaki dealer for the dust boot and retaining clip. They appear to be still available from Kawasaki. The stopper is no longer available from Kawasaki. It looks like the folks at this link ( www.cyclebrakes.com/MC%20Rebuilds.pdf ) sell kits for the FRONT - see kit #32-8052. Ed

Cheapest solution so far is to use a Ninja rear master, but you have to do some fabrication. The best part is that it feels exactly like the stock one because the piston is the same size.

www.kzrider.com/forum/5-chassis/531950-a...l=component&type=raw

Better make sure the master bore is not pitted before you spend a bunch of cash on internal parts. There is a very good chance that the bore is trashed if someone neglected to keep fresh fluid in the system.

Took it apart & eeccchhh! Blobs of coagulated orange goo. I can machine up a new piston from brass on my lathe, & make a new retaining washer also if I need too. The seals may be hard to find, have to try a hydraulics store. Haven't looked at the bore yet but I am pretty sure I know where the orange came from. I may try a flex hone but those buggers are $35.

Maybe I can find a used one with a good (better) bore?

SweetGPz wrote: Took it apart & eeccchhh! Blobs of coagulated orange goo. I can machine up a new piston from brass on my lathe, & make a new retaining washer also if I need too. The seals may be hard to find, have to try a hydraulics store. Haven't looked at the bore yet but I am pretty sure I know where the orange came from. I may try a flex hone but those buggers are $35.

Maybe I can find a used one with a good (better) bore?

Maybe. I found a really nice one for my 750. The problem is finding a seller willing to look inside.

SweetGPz wrote: Hi All,
Nearly done with the brakes and ready to roll. I cannot find many of the rear master cylinder parts and no one I can find sells a rebuild kit with all the rubber bits. N/A from K&L and discontinued by Kawasaki. According to partzilla the piston is the same as the front m/c. Is there any source out the for the dust boot, piston stopper & retaining clip etc? The bores and seals have to be pretty common...

Alternatively is there a stock looking interchange of the entire unit?

TIA,Bill

Actually, the front master cylinder has a 5/8" bore and the rear has a 14mm bore, The "82 GPZ550 also has a 14mm rear master cylinder and the rebuild kit for it was still available, last time I checked.. The piston is slightly different on the end where the rod/linkage attach. So you might be able to fabricate the linkage to fit yours or use the seals out of the '82 kit on your old piston, if the piston and bore are serviceable. Good luck!

GPZD1,

That is info I can work with, thanks. Any chance I can ask you to pull back the boot and shoot a cell photo of what the piston link connection looks like?

Turns out my bore looks OK, piston is not so hot. But I have a lathe and can machine a piston to a smaller diameter. Easier than making it from scratch.

TIA,
B ill

SweetGPz wrote: GPZD1,

That is info I can work with, thanks. Any chance I can ask you to pull back the boot and shoot a cell photo of what the piston link connection looks like?

Turns out my bore looks OK, piston is not so hot. But I have a lathe and can machine a piston to a smaller diameter. Easier than making it from scratch.

TIA,
B ill

My setup is like yours, witch is a ball and cup connection. Attached is two photos.

No eBay APP ID and/or Cert ID defined in Kunena configurationHere is a link to the linkage the 1982-83 GPZ550 uses, so you can purchase a piston and seal kit for the 82-83 and install it in place of your old piston, if you desire.

No eBay APP ID and/or Cert ID defined in Kunena configurationBelow is a link to the K&L piston and seal assembly for the '82-83 GPZ550. The piston and seal assembly appears to be available for the 82-83, Kawasaki part # 43020-1019, which you can purchase at Partzilla.com for $ 37.48.

So, replace the brake fluid every 2 years from now on. That's what I do. Parts and rebuild kits are getting harder to come by.