Master Cylinder for the front break is leaky

So I had to drill out the top screws of the front brake cylinder reservoir and found that all the old oil was dried up in a crud. I cleaned it all up, flushed out all the old brake fluid, added new brake fluid and bled the brake system to the best of my ability (this was my very first brake fluid refill and bleed job). The brake seemed to hold and everything was good until the next morning when I saw that the brake fluid was leaking like crazy from the side of the cylinder, where the fluid comes out of the cylinder. The leak is pretty significant and I'm sure that my reservoir is empty by now.

Before I jump the gun and buy me a replacement cylinder from ebay, I was wondering if there was any hope in salvaging the one I have? Could I get away with replacing some o-ring's and such? For your reference, the leak is where the part 92022 is in this diagram:

www.motosport.com/cruiser/oem-parts/KAWA...NDER-('82_'83-C3~C4)

Thanks in advance as always for your help.

I didnt see the part where you rebuilt the master cylinder with new parts????

check for cracks, rebuild master with full rebuild kit, install new bango crush washers....check hose....you should be good

No eBay APP ID and/or Cert ID defined in Kunena configurationAny pointers on which rebuild kit to use? This is for a kz550-c3 (1982) LTD. Just like this one:

Z1-ENTERPRISES

(315) 926-5054

EXT 117 ASK FOR CHRIS

No eBay APP ID and/or Cert ID defined in Kunena configurationI also see this on ebay:



Does anyone know if this works on my cylinder?

P.S: I left a message for Chris at Z1

Realized that the relief valve was blocked by some junk and once I cleaned the whole thing up, everything is working just fine and I see no leaks or such.

Glad you got it going. From what you said about it leaking from the sealing washer, sounds like all you needed to do was snug up the line and you would have been good to go.

Yeah, mostly true. But it took a bit of a prying and pushing to open up that relief valve that was stuck pretty bad. Since this was my first time, I didn't realize that there actually supposed to be a hole there since it was so tiny and I couldn't push anything in the first time around. But my carb cleaner kit came in handy this time. Since the extra fluid did not have a way to get back into the cylinder through the relief, it started to push out of the tube end.

Bunty27 wrote: Yeah, mostly true. But it took a bit of a prying and pushing to open up that relief valve that was stuck pretty bad. Since this was my first time, I didn't realize that there actually supposed to be a hole there since it was so tiny and I couldn't push anything in the first time around. But my carb cleaner kit came in handy this time. Since the extra fluid did not have a way to get back into the cylinder through the relief, it started to push out of the tube end.

What relief valve are you referring to? What hole are you talking about?

The little hole inside the resevoir would be my guess,care with petro based cleaners around the rubber sealers it will swell them up

BlackZ1R, in the rectangular Master Cylinder that I have on my KZ550 LTD('82), there are two holes at the bottom. One is a large hole (around 1-2mm in diameter) through which the brake fluid is forced by the action of the brake lever into the supply port and finally into the brake cable. There is another really really tiny hole called the relief which is closed due to the brake lever action but is opened (to the supply port) when the lever is not pressed and helps take back the unused/excess fluid into the master cylinder until the fluid pressure drops to zero. If this relief valve/hole is blocked, there is no place for the excess fluid to go anywhere which results in the leak that I noticed. Please refer to Pg.199 in the KZ550 service manual for detailed explanation with pics. You can find the links to the manuals in Lou's signature.

Hello I have the same master cylinder problem on my 82 KZ1000LTD. Right now it is dry, no fluid. The bike has set in my garage for about 10 years. SO maybe this will help me figure out where the brake fluid leaked to. The black paint around and under the brake handle has this grey crud kid of built up. Would that be from the leaking brake fluid? I would appreciate any advice or web links to this problem. I haven't even checked the back brakes yet. Just starting to restore the bike. Thanks.

Wesley