1978 Kawasaki Z1R front master cylinder disassembl

Hello,

I have a master cylinder with a frozen piston and I need some guidance on how to disassemble it. According to bikebandit.com schematics, there is a plastic liner in front of a piston seal and stoper ( www.bikebandit.com/oem-parts/1978-kawasa.../o/m150627#sch550240 ). I am unsure of how to remove this plastic liner. It appears there is a channel that runs behind the plastic liner; is there a tool or technique that is used for the removal of this part? I have been very nervous about messing with it as it appears that spares for this part no longer exist in the inventory.

Thank you.

The piston liner (#13) has a couple of tabs that need to be depressed. Your mc doesn't appear to have holes for the tabs. It looks like you'll have to pry at the grooves. Mine has rectangular holes where you use a thin blade screwdriver to depress the tabs.

1000D - Z1R --- 14008-1007

The several that I have worked on were exactly as described by Martin
I don't think this is a stock OEM M/C the 5/8 being my clue, back in 78 almost all labeling
like such was in the metric system
Lack of the clips to hold in the liner may have been the way around patent/payment or whatever issue
There doesn't appear to be anyway other than what Martin described, at least till some of it is exposed above the bore
Good Luck

EZ

His master cylinder might be stock. From the parts diagram link he provided, it appears the same as his photo. I did not know the Z1R had such an unusual mc --- I've never seen that one before.

michaelcress wrote: I am unsure of how to remove this plastic liner.

The plastic piece has a tab that sticks out on each side that lock it in place. You need to push something flat in there and fold the plastic retainer in towards the center. It bends a bit like a taco. Poke here:


Behind the plastic piece is the rubber boot. That should just pull out, but it often gets pretty crusty under the boot so it may tear. A replacement boot should still be available.

Behind the boot is a C shaped washer. Again, this would normally fall right out if it's not all crusty.

After those three pieces are out, the piston should pull out. If it's stuck you're going to have to get creative.

Finally, if you do get the piston out, this thread might be useful:
kzrider.com/kunena/5-chassis/569907-z1r-...build-kit-substitute

One final note. You should definitely remove the reservoir tube elbow at the top and clean out the two small holes that feed into the cylinder. The smaller of these two holes is nearly always plugged, and you'll never be able to bleed air from the MC unless this hole is open. If you need something to poke it, these work well.
K&L Carb Cleaner Wire Set

Good luck.

martin_csr wrote: I did not know the Z1R had such an unusual mc --- I've never seen that one before.

This is definitely the stock Z1R MC. It's cable actuated. There really isn't anything else like it.

I believe they did this because the edges of the fairing came too close to the handlebar to fit the standard MC they used on everything else with integrated reservoir.

I also think they got the idea (and the general shape of the fairing and dashboard) from the BMW R90S. The BMW MC is cable actuated and mounted under the front of the tank.

Thank you all for your help. I did get the plastic tab and rubber boot out. However, the C clamp and piston are still in there. The C clamp looks to be prevented from coming out by the flared lip of the piston. The piston isn't budging without a solid whack.

I have seen comments about hooking it up to another M/C and pressurizing the piston cavity. Has anyone had any luck with this?

I was finally able to extract the stuck piston. Below is a summary of the setup and removal procedure that worked for me.

Note: This assumes that the plastic piece above has already been removed.

1) Lock master cylinder assembly in place using two screwdrivers. One should be inserted through the hole that the piston lever attaches to in order to serve as a fulcrum point (black screwdriver in attached photo)
2) Position the lower jaw (right handle in picture) of a pair of channel locks over the screwdriver/fulcrum point (black screw driver in picture) and underneath the lip of the stuck piston to be extracted.
3) Ensure vice is secure. If using a Craftsman workmate like I was, ensure that the fixture is tight and apply weight to the setup (step on the Craftsman workmate step) to prevent movement.
4) Slowly lever the piston using the lower channel lock jaw until no more purchase can be obtained (the channel lock jaw slips off)
5) Remove channel locks and pick up normal claw hammer.
6) Loop hammer claw underneath piston and use outer lip of master cylinder housing as a fulcrum point. Lever out remainder of piston.

I hope this helps someone else.

A couple of questions to keep me thinking straight
1.) Is the piston now unusable? Was it already in that shape due to being stuck.
2.) Is there damage to the bore?
3.) Can you tell what was/is the cause of the piston being stuck
4.) Keep us informed as you get this back together, if you could

Thanks

EZ

Glad you were able to get it out. The worst part for me was removing the white plastic retainer clip. It came out fairly easy, but it's the one part you can't buy. Break it and your M/C is basically scrap. I'm always nervous flexing 39 YO plastic that can't be replaced.

Glad you were able to get it out. The worst part for me was removing the white plastic retainer clip. It came out fairly easy, but it's the one part you can't buy. Break it and your M/C is basically scrap. I'm always nervous flexing 39 YO plastic that can't be replaced.

Another candidate for 3D printing?

michaelcress wrote: I was finally able to extract the stuck piston.

Given how much effort was required to remove the piston, I'm guessing the cylinder wall is going to look bad. If you missed it, this recent thread gives several recommendations for companies that install sleeves in master cylinders.

kzrider.com/forum/5-chassis/606174-re-sleeving-master-cylinders

I found a spare Z1R MC with a stuck piston, but not as stuck as yours. The cylinder walls were pretty scored. I used a ball/flex hone to clean it up, but never actually reassembled it to test. The hone made the walls shiny and removed the scoring, but the bore looked wavy to my eye. It wasn't exactly what I was hoping for, but you might have better luck. I bought my flex hone from this site: www.brushresearch.com/