KZ 650 Master Cylinder kaput?

'79 KZ650 B3

While in the process of fighting electrical problems for the past several months, today I noticed the master cylinder is leaking. Yay!

I pulled on the brake lever a few times, and it's mushier than normal. When we replaced the brakes pads, we had a terrible time getting the front brake bled. Even when we got it as good as we could, it still felt mushy.

The bike has dual calipers on the front, and drum on the rear. I'm almost certain it was a single caliper front setup from the factory. I noticed today that JCCWall's 81 H1, which has dual front brakes, has a bigger mastercylinder than mine does. We're pretty sure a previous owner swapped over to KZ750 forks, brakes, etc.

It got me to thinking, do the dual caliper setups have a bigger master cylinder? If so, and my bike still has the single caliper master cylinder, coyld that be what is causing the mushiness?

If this is the correct master cylinder, am I better off replacing the master cylinder, or rebuilding it? My buddy said his was leaking, so he just put some Trans-X in it. He said it quit leaking.

I'm a little suspicious.

On the underside of the M/C it should say 5/8. This is the standard size on the single-piston, dual caliper models. I do not know what Trans-X is, but it is at best a band-aid. Repairing is always better, especially when it comes to an essential part of the bike such as this. It is not difficult to fix as long as you check with your factory manual whether you're doing things right.

According to the Clymer manual, there were 2 different sizes of m/c. One for single caliper, a bigger for dual caliper. The dual caliper needs a larger piston to push enough fluid quickly enough for quick stops.
My bike had the smaller m/c installed w/ duals; I put the bigger one on it. If I were you, I'd replace it. It may work fine for most stops, but when you really need it, it may not perform for you. 100 bucks is a small price to pay for the comfort/safety level. But the bleeding part is so hideous:S

I don't see a master cylinder on the z1enterprises.com website. Cany anyone tell me where to get one?

ebay

seanof30306 wrote:

'79 KZ650 B3... master cylinder is leaking... dual calipers on the front...single caliper front setup from the factory...pretty sure a previous owner swapped over to KZ750 forks, brakes, etc....

A used m/c from eBay or anywhere else may be in worse condition than already have. Would consider rebuilding present unit. Must dissassemble to clean and inspect bore. Minor pitting inside bore is not a big deal and may be lessened by polishing. Kits include new piston and cups.

Need to determine type m/c (barrel, trapezoidal, etc.) and size of bore, which is as already mentioned usually embossed on the underside (usually either 14mm for single disk or 5/8" for dual disks).

Different type m/c involve various disassembly techniques.

Could a photo of the current m/c be posted???

Good Luck!

found this on ebay. Anyone have any experience with them?

cgi.ebay.com/ebaymotors/FRONT-BRAKE-MAST...9QQitemZ120306022529

Patton wrote:

seanof30306 wrote:

'79 KZ650 B3... master cylinder is leaking... dual calipers on the front...single caliper front setup from the factory...pretty sure a previous owner swapped over to KZ750 forks, brakes, etc....

A used m/c from eBay or anywhere else may be in worse condition than already have. Would consider rebuilding present unit. Must dissassemble to clean and inspect bore. Minor pitting inside bore is not a big deal and may be lessened by polishing. Kits include new piston and cups.

Need to determine type m/c (barrel, trapezoidal, etc.) and size of bore, which is as already mentioned usually embossed on the underside (usually either 14mm for single disk or 5/8" for dual disks).

Different type m/c involve various disassembly techniques.

Could a photo of the current m/c be posted???

Good Luck!

My digital camera is dead, but this is the exact same one

Patton wrote:

seanof30306 wrote:

'79 KZ650 B3... master cylinder is leaking... dual calipers on the front...single caliper front setup from the factory...pretty sure a previous owner swapped over to KZ750 forks, brakes, etc....

A used m/c from eBay or anywhere else may be in worse condition than already have. Would consider rebuilding present unit. Must dissassemble to clean and inspect bore. Minor pitting inside bore is not a big deal and may be lessened by polishing. Kits include new piston and cups.

Need to determine type m/c (barrel, trapezoidal, etc.) and size of bore, which is as already mentioned usually embossed on the underside (usually either 14mm for single disk or 5/8" for dual disks).

Different type m/c involve various disassembly techniques.

Could a photo of the current m/c be posted???

Good Luck!

My digital camera is dead, but this is the exact same one

www.cgi.ebay.com/ebaymotors/KAWASKI-79-K...6QQitemZ260278226548

Sorry wasn't more clear -- was noting need to determine style and size of m/c to assure ordering the correct replacement parts needed (i.e., getting the correct kit).

For example, different style m/c with same bore may have different piston design. Am guessing a barrel 5/8" would likely use a different piston than a trapezoidal 5/8".

Good Luck!

well, for some reason, it won't display the ebay links. when i click on "edit", tyhey're there, but they don't show up.

cgi.ebay.com/ebaymotors/KAWASKI-79-KZ650-KZ-650-BRAKE-MASTER-CYLINDER-FRONT_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQitemZ260278226548

edit: ok, no link, but there is the address of the 14mm trapezoidal m/c that is off a '79 KZ650, same model as mine.

cgi.ebay.com/ebaymotors/FRONT-BRAKE-MASTER-CYLINDER-KZ200-KZ550-KZ650-KZ700_W0QQcmdZViewItemQQ_trkparmsZ72Q3a570Q7c39Q3a1Q7c66Q3a2Q7c65Q3a12Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem120306022529QQitemZ120306022529

and here is the address of the new one on ebay. you just have to put:

http://

in front of them

Here's the one I bought. Quite pleased with it.

tinyurl.com/4lvu5m