Rear Brake Master Cylinder 79 KZ650

Hey, This is my first post here on KZRider.com. I searched but couldn't really garnish what I needed to answer my question from previous posts. I have a 79 KZ650 SR that I am rebulding and I'm pretty sure the rear brake master cylinder is shot. I have removed the calipers trying to use a wrench handle as the simulated rotor and raised them so the bleed nozzle is the highest point in the system before trying to re bleed them, I have pumped and pumped and pumped and no pressure seems to build in the line at all. I removed the banjo bolt on the master cylinder and placed my finger over the hole to simulate a closed bleed nozzle and pumped the brake a few times. I felt no pressure at all coming from the cylinder. I have looked almost everywhere I know of for a rebuild kit and have not been able to find one SO... I was wondering. Could I swipe a working master cylinder from a KZ900 or similar model? Or can I pirate the parts out of an existing/functioning 900 or 650 cylinder to use in a "home brew rebuild" ? Does anyone know if rebuild kits for my rear master cylinder exist?

Have you tried Z1enterprises?

dahltron wrote: ...pretty sure the rear brake master cylinder is shot....

Hello, dahltron, and WELCOME to KZr!

Even a horrible looking master cylinder may sometimes be refurbished to useable condition, especially where the bore isn't too badly pitted.

Requires thorough cleaning, dressing the bore, clearing the supply and relief ports, etc.

The FSM should include a diagram showing exactly how the master cylinder is supposed to function during application and release of brake.

If needed, here's a down-loadable on-line version of the Factory Service Manual (FSM).

Click > jarlef.no/Kawasaki/Series/Z/650/z650files.htm



With a FORUM SEARCH, may find several good threads here on KZr about resolving master cylinder issues.
But in any event we'll be happy to walk ya through it.

Good Fortune!

Welcome aboard. I suggest you disassemble the rear MC, clean it, and inspect it to see which part(s) are causing the problem. If the problem is the bore of the MC, depending upon how bad it is, you may need to replace the whole unit. If it is simply the primary cup you can just replace it; this can be found even though no "kit" is available. Let us know what you discover. Here's what you will find inside the MC:

cup primary 43019-001 available here.
www.powersportsplus.com/parts/detail/kawasaki/KP-43019-001.html

SPARKY47 wrote: cup primary 43019-001 available here.
www.powersportsplus.com/parts/detail/kawasaki/KP-43019-001.html

Unfortunately www.powersportsplus.com is one of those crappy sites that shows a price for every part for every model Kawasaki as if they can supply it, but notice their web page says "Product Obsolete." You can try them, but I can assure you they simply order available parts from Kawasaki on an "as needed" basis rather than carrying an inventory of parts. So when Kawasaki tells them the part is no longer available they will refund your money. Meanwhile you have lost time fixing your bike. Sadly, they are not the only site that pulls this crap. The good news is, very many obsolete parts are still available if you search the right places that actually carry an inventory. Here's an example of www.powersportsplus.com bullcrap. In the link below they show a price for a new frame for a 1973 Z1. In fact, they will show a price for every part of a Z1 or any other bike even though there's no way they can deliver.

www.powersportsplus.com/parts/detail/kaw...i/KP-32002-1018.html

Thank you so much guys. I've checked out all of the info you guys have gotten on this and am going to pull the MC and clean it today. @Patton That manual is for the 81 650D4 and I have the earlier 79 650D2 version, The parts aren't drastically different though right? As far as the MC goes..It doesn't even look like it has a cup primary on it Which may be the issue. I'll Post some pics as soon as it gets pulled. It's not leaking or anything so I'm crossing my fingers that the internal o-ring is in good condition. @Sparky47 other than grabbing one that doesn't look too thrashed off ebay is there anywhere I might be able to source a new-ish cup primary if powersports + douches out on me? You guys are awesome and this is a wonderful community. Thank you guys.

Let me know if you can't find a primary cup. I think I can find a new old stock (NOS) source. Ed

Thanks 650ed, I didn't realise they pulled that crap.Makes me wonder who else does the same?
Someone should make a bunch of these primary cups,they seem quite the difficult little ******* to find.
Anyhow thanks again!

SPARKY47 wrote: Thanks 650ed, I didn't realise they pulled that crap.Makes me wonder who else does the same?
Someone should make a bunch of these primary cups,they seem quite the difficult little ******* to find.
Anyhow thanks again!

No problem; they fooled me a little while back too. I saw they had a price on a part I wanted, but then I saw they had a price for everything and realized they did not delete prices for items they cannot deliver. Ed