Leaking front brake master cylinder

I noticed something on my fuel tank. So I cleaned it off and put a coat of was on it. Next day the spots were back. That is how I discovered the master cylinder is leaking. Check the 4 screws on top and they are all tight. The Reservoir is down a little. First thing I searched for was replacement gaskets, but found none. I did find a replacement reservoir. It seems simple enough to swap out. Picture of my reservoir and the site of the replacement screenshot. Just looking for red flags is all, that is better to rebuild the master cylinder and get the parts here. Or you do not want that replacement part. TIA



fd

Is it just the picture or is it wet around the sealing washer on the banjo bolt ? Could just need a new pair of sealing washers ?

That sort of parts listing is really annoying

The large print says "OEM" and includes a Kawasaki part number, clearly intended to mislead buyers into thinking they're getting actual Kawasaki parts.

Then the smaller print says "Excellent quality Preproduction". (I'm assuming that last word was supposed to be 'reproduction'.)

I get that the part (allegedly) has a lifetime warranty and yes, people need to read and be aware of what they're doing, but it still strikes me as shady/deceptive.

Nerdy wrote:

The large print says "OEM" and includes a Kawasaki part number, clearly intended to mislead buyers into thinking they're getting actual Kawasaki parts.
 

At least they show a photo of the actual item, and admit that's is a reproduction.

There are ebay sellers who sell reproduction parts but show a photo of a true OEM part along with the OEM part number tag, even when the part they sell looks obviously different from the OEM part.
I'm looking at you retro-motorcycles

I don't have a problem with vendors who sell quality reproduction parts, but they should describe them as that.  But then I suppose the crap parts vendors would list theirs the same way.   

Wookie58 wrote:

Is it just the picture or is it wet around the sealing washer on the banjo bolt ? Could just need a new pair of sealing washers ?

It does look like it could be the sealing washers. I'd wrap a paper towel around the banjo bolt and see if it's wet after a while. If it takes too long maybe ziptie the front brake lever to put a bit of pressure on the system. 
If it's not that I'd think it would be the leaking around the piston as the reservoir looks fine (at least from the side you took the picture from). In this case you can get a repair kit but given the price of the replacement cylinder and the price of a repair kit it might not be worth it.

A little low-down on those trapezoidal style Tokico's. When they changed from the round reservoir to the trapezoid and rectangular style they did something interesting, used a steel liner for the piston bore. This started around 1978. They only did this for a short time though. Problem was pitting of the steel insert due to moisture. So..if it's not just a simple tightening of the banjo or washer replacements, i would remove the internals and have a "REAL" good look inside before ordering any replacement bits. Looks like you are missing some paint on the top by the lever too. There is an oring under the reservoir too but if you don't see fluid drooling out around the mating surfaces then it's not coming from there. Tanner at Z1Parts does good warranty support. If You are wanting to maintain "original" and find yours is also pitted, and not in a hurry. I send out all my Master cylinders to Karps in California. He re-sleeves them with a stainless steel liner and re-drills the two holes.     

Sorry, I didn't actually answer your original questions.

If you want to rebuild you existing master cylinder, I've had good luck with K&L rebuild kits.  
z1parts.net/front-kawasaki-master-cylinder-rebuild-kit-32-8048/

However, lately I've been buying brake part from Brake Crafters, and so far everything I've received has been high quality.  This kit is both cheaper and comes with the sealing washers for the brake line.
brakecrafters.com/collections/1978-kawas...kawasaki-kz650b-z650

I would say it's definitely worth the effort to disassemble the master cylinder you have and inspect it for pitting as  asphalt900  suggested.  If the bore inside looks relatively smooth and in good condition, then there is a good chance that a full rebuild will solve the leaking.

One thing to note.  There are two fluid transfer holes between the reservoir and the cylinder.  These often get clogged, and one is very small.  Both holes need to be open.
www.kzrider.com/forum/5-chassis/608766-f...rake-reservoir-holes
kzrider.com/forum/5-chassis/612533-1980-...ront-master-cylinder
  

No disrespect to DOHC, but I've had the opposite experience with K&L brake system parts.  I've personally experienced caliper piston seals that were too large, causing the piston to bind in the caliper bore, and a master cylinder kit that was warped, causing it to scrape in the bore of the master, destroying the casting.  Use at your own risk.

Personally, when faced with a leaking master, I throw it away and get a better one.  I can appreciate that some guys with Z1's want to maintain originality, but for a 650?  I wouldn't bother.  I like the EX650 masters.  You can find low mileage used units off eBay for cheap.  They have the proper threaded mirror lug also.  

Ditto Ness on the replacement! And Yes, as mentioned before you re-assemble, clean out that TINY relief hole! I'm sure it's clear as of now because i'm assuming because you didn't mention any "binding" issues. A trick i use, because the hole is soo small, is take apart a BIC lighter and use the spring. It's small/thin enough to initially knock-out any immediate debris. And..once assembled, you should be able to put that spring down the hole extending into the bore. Then VERY lightly pull the lever, you will be able to see the end of the spring move within the reservoir. Why do this? It verifies the cup rubber, one that goes over the big spring, isn't covering this little hole at it's resting position. The position of this cup is controlled/set by that U shaped washer looking thing that goes under the assembly circlip. It's thickness or lack of determines how close/far away this cup's lip sits in relation to that little hole. Of course piston length also plays a huge role too. I've always has success with K&L but thinking those Tour Max ones are a major problem. The rubber is "shiney", leading me to think it's, sound like a broken record here but that Chinese rubber.