Broken-Hearted over '78 kz1000 rear brake!

I would have went with something like this-
cgi.ebay.com/ebaymotors/Kawasaki-KZ650-K...?hash=item2a0370008b

donthekawguy wrote:

I would have went with something like this-
cgi.ebay.com/ebaymotors/Kawasaki-KZ650-K...?hash=item2a0370008b

Thanks Don, CLOSE! Almost, but that model has the fluid reservoir as a separate piece connected by a hose. It's a later model.

Curse me all to heck, I don't get it -- these durned '78 A2 models with the rare rebuild kits! You can get them for under $40 for any year KZ *before* '78 and *after* '78 but not '78 itself. It's like when they'd show a video on the TV news of grocery stores in Russia, nearly empty store shelves, a couple loaves of bread only, and still have a hoard of shoppers standing outside ready to stampede.

I reckon we got 'Central Planning' here for the '78 kz1000 A2 rebuild kits.
Damn Commies.

If you can't find the rebuild kit, you may want to consider getting a rear Brake master cylinder off a Bike that you can get a rebuild kit for and adapting it to your bike. Don't know if it feasible, but at least worth thinking about.

Agreed. That's down the road a bit. I could pony up the $72 to buy the kit from Z1. Just now, I've inspected the parts that I currently have and everything looks OK, there was just a ton of dried-up brake fluid inside the thing. The bore is smooth, the spring is fine, the other parts including the 3 rubber parts are in good shape.

Today, now that the MC is completely disassembled, I'm going to use my air gun and blow out all the dried up gunk, then re-assemble it, fill with brake fluid and mount it on the bike and see if she works.

WHAT DO YOU ALL LIKE TO USE TO CLEAN THE MC AND ITS PARTS?

To me, the only safe thing is to flush it with Dot 3 brake fluid to avoid contamination. Otherwise I'd be using carb cleaner or lacquer thinner or some other solvent.

Here's what the parts look like:



Here's the spring and the gummy substance that I removed from the small end of the spring that has the rubber platen (left side of the spring in the photo) -- it is only about 1/8th of the entire load of such gummy junk to come out of the Master Cylinder bore and orifices/channels:




Here's the bore -- the light shiny part is the smooth part of the bore, it's like a super-smooth gun barrel sans rifling:

Hi and sorry for the delay. Your master cylinder looks identical to the master on my '78 kz1000 LTD! I would either look at Z1 Ent. for the LTD model rebuild kit or check SIRIUSCONINCNOSPARTS in E-Bay. The Z1 Ent. kit is factory and I would rather go that road personally in order to get optimum part fit. K+L parts have come a long way in quality and the other link will probably get you what you need for about half the price. As far as cleaning the bore, I usually use some of the fine 3M scouring type pad material wrapped around a piece of 1/4" dowel making sure that I only twist it once inside the bore and not in and out of the bore as that will leave small scratches the length of the bore which is not desirable. Stain-type marks are o.k. to leave as they shouldn't affect the plunger seal but you don't want to scratch it.

Thanks Kawboy -- I checked with siriusconinc and they seem to not have it just now for the '78 kz1000. According to my parts list and factory parts cross-reference, the following bikes use the same rear master cylinder internal parts:

- 1976-79 kz750, B1 through B4 models
- 1976 kz900 B1
- 1977-79 kz1000 A1 through A3A models
- 1977-79 kz1000 B1 through B3 models
- 1978-79 kz1000 C1 through C2 models (police bikes)
- 1978 Z1-R kz1000
- 1979-80 kz1000 E1 and E2 shaft drive models

NOT A SINGLE *affordable* kit (less than, say, $50 bucks) can be found by me, I checked Z1, Redline, ebay.


I will take your advice re: cleaning the small 'ring' that's visible quite deep in the bore -- good advice there, and I will try to reassemble and test tomorrow.

By the way -- what would you recommended using as a cleaning solution for the parts? I was thinking of using 'Brake Cleaner' but I suspect those products are *not* for the insides of master cylinders. What say you?

If you totally disassemble the master, including the reservoir, and the o-ring below it, then I would use isopropyl alcohol with a q-tip to go over the housing internals. Wipe down your o-rings with a clean cloth. Check around the plunger seal to make sure there is no "caca" wedged under the lip of it and whatever you do, don't pick at the valve flaps at the end of the plunger as they will not bend back! Blow all cleaned parts with your compressor gun and assemble. Make sure you put a small amount of brake fluid on the internals to make assembly smooth but don't get any on the master if it has been repainted. If the bore is really smooth and clean, just use the alcohol and forget about the abrasive.At some point in time, if you don't have a tabletop parts washer, get one as I find they are invaluable and pretty reasonable.

By the way, I have found that Turtle Wax Wheel Black works great to bring back the softness to most rubber parts unless they are about to crumble. I have sprayed a bit onto grommets of all kinds, brake master cylinder boots, o-rings etc., then put them into zip-lock bags until ready to use and it is unbelievable how much it soaks in and rejuvenates the rubber. This would work for the boot on the end of your rear master as well!

Hi

I'm having a small problem with the rear master cylinder on my 1979 kz1000 b3, the parts look exactly the same as the pics above, i have the piston out bu there is more up the hole, the spring and another seal by the looks of the pics, i have a clymer manual which doesn't show anything usefull for the master cylinder, how do i get the other seal and the spring out from the cylinder, i'm asking here cos i dont want to wreck anything by having a go first thanks

The ONLY parts available are genuine Kawasaki parts.

I went through this with my project kz a couple weeks ago. I cleaned the rear master out and reassembled it with the old pieces. No leaks so far and it works great.

One thing to try when you go to bleed it out...pour some brake fluid in the outlet where the banjo bolt goes in before connecting the hose. It primes the M/C and makes it a heck of a lot easier and quicker to bleed the rear caliper.

As far as that seal and spring inside the M/C - use a pair of needle nose...it's just a rubber cup inside there, and the spring should just fall out when you pull the rubber out.

Later
Phil

Here is a diagram from the Kawasaki shop manual for the 78 A2A but it should be similar to yours.

I would soak it in Dot3 to try and soften up the dry fluid , wear gloves and keep it away from anything painted.

After a few days try again to remove the parts.

Once the parts are out clean the master cylinder with rubbing alcohol "real good" and repaint with VHT caliper paint and bake in an oven as per instructions.

My wife loved that part

Good luck