Z1R Front Master Cylinder Rebuild Kit Substitute

edit your post and remove the url for the pic.

i use
resize.it
to make them 1089x817 it seems to be a size that posts well,and still gets big when clicked.

hth,

leon

G'day Guys, an update on the Z1-R front brake rebuild - FAILURE !

After carefully re-assembling the calipers with all new seals, dustboots and connecting the (new) hoses with (new) banjo bolts and crush washers I was ready to bleed the bleeder! I fitted the substitute front m/cyl piston kit from Z1Enterprises but have not been able to get any hydraulic pressure at the lever. I initially get some fluid out of the bleed nipples when going through the bleed process (per manual) but then nothing else comes out. I checked all the banjo bolts and connections - all good and no blockages or leaks. I even primed the calipers with some brake fluid then sucked it through the bleed tube but still no pressure. I pulled the M/Cyl apart today and all looks as per the parts book and the substitute piston is definitely the one specified at the start of this thread and is not damaged/broken/mis-fitted. Any thoughts suggestions would be much appreciated !

After reading the theory of operation of the braking system in the workshop manual I had a real good look at the MC especially the barrel - I noted that only the supply port is machined into the chamber/barrel of the M/C, the relief port goes nowhere - it is not blocked it has never been drilled though. Can somebody please confirm that these two ports should be visible in the barrel of the MC? I've attached a pic of the barrel of the MC to show the detail - only one hole is visible ,



the other is not blocked - just not drilled. i don't know the history of the MC - may have been replaced somewhere by a PO and the bike may have never been used with this installed - I bought the bike as a basket case so....?

As soon as I started reading your post I decided you have a blocked relief port, but it seems like you already know that.

That hole definitely needs to be open. In the past when that hole was blocked I spent hours trying to get the system to pump up with no luck.

As far as not being able to see the hole inside the bore, it is a very small hole. Much much smaller than the supply port . Could it be that the opening in the port has been packed with rust and grit and smoothed over by the movement of the piston?

I would say you should remove the plastic elbow at the top of the MC and try opening up the hole with a sewing needle or similar. If it really is un-drilled that would be really surprising. But if that is the case I can try to estimate the size of tiny drill bit you'll need...

I assume you already have the shop manual with this diagram?

Thanks dohc for your prompt reply - much appreciated! Sounds like you have identified the problem. Yes I have this diagram and I have the MC completely disassembled ready for any work. if you could please let me (and our brethren) know what size this hole this should be (maybe a caliper measurement of the needle diameter - if possible) then I can clear the hole and get on with the bleeding process!

Further to my last post, I have carefully cleaned the top of the area of the MC where the supply and relief ports live. I can see a tiny impression where the relief port is but it is completely blocked and does not make it through into the compression chamber - pic attached for reference. Looks like about a .010" diameter hole -but will wait until hole size is confirmed before I go messing with it! I don't expect anyone to strip their braking system just to do this but if anyone has a Z1-R MC apart on their bench and if they could post an accurate measurement of the relief port hole dia it would be much appreciated! Otherwise I'll just use a tiny needle to poke the gunk out of the hole and clear it, hopefully without increasing the hole dia.

I do have a Z1-R MC, already in pieces, that I can look at, but I haven't had a chance to dig it out yet.

Also, nice picture! Many people struggle to get clear close-up pictures like that.

I recommend getting this carb cleaning tool from Z1 Enterprises:

www.z1enterprises.com/ItemDetails.aspx?item=KL35-3498

I have been working on my bike and had issues with the cylinder pumping up to bleed the brakes. This is what I did, sounds crazy I know, I pulled lever in and tied it to the handlebars and left it overnight. The next day voila, it worked. Now, I noticed your cylinder looked really pitted, could be an issue there. Not with the holes being plugged as you saw they looked clean.
Make sure your reservoir is full.
I spent hours trying to pump up my brakes after taking system apart and thought WTF and then read about that little trick on the forums and several people had mentioned it so I figured I would give it a shot. I am concerned with the pitting on the cylinder though. That does not look good at all.

Thanks dohc - would really appreciate if you could confirm the relief hole dia. The pic was a bit tricky - had to use the digital macro function with supplementary lighting carefully placed so's not to get too much glare. Regarding the carb tool - good idea not only for this job but for when I get to the carbs - although I have bought a complete ovehaul kit for the 4 carbs and will be changing out all jets after I get the bodies vapour blasted.

G'day saxjonz - thanks for your tips and your concern about the condition of the bore in my MC. It's actually quite smooth with more discolouration than pitting. It's pretty hard to get the camera to get a clear pic of the bore as it tries to focus on the nearest object (outer rim) . If I get too close to the bore the light is blocked out and there's no image. I think dohc has "cracked it" so I'll hopefully get the bleeding done later this week. I'll keep your tip about keeping the lever pulled back filed for future reference.

Hi Bill, twin disks can be a bitch to bleed up, in some instances, as l had to with my recent A4 resto, the calipers
and T junction need to be higher then the master cylinder, if after cleaning out your hole still won't bleed up try this, l think the pic explains it all, don't forget to put a 5 or 6mm packer between brake pads.

saxjonz wrote: I pulled lever in and tied it to the handlebars and left it overnight. The next day voila, it worked. Now,

I did this accidentally. Spent an entire afternoon trying to bleed my 650 but no matter what I did the lever just pulled all the way to the grip. I eventually gave up and walked away, but when I came back the next day it had fixed itself. Gravity!! But there is no reason to lock the lever in. That would just block the ports to the reservoir. If this method is going to work, gravity will either bring the air to the top or it won't. The lever position doesn't matter.

weales wrote: ...would really appreciate if you could confirm the relief hole dia...

I have good news and bad. I found my master cylinder, and the carb cleaning kit (which I used as a gauge pin set). The bad news is that I can't find my micrometer or calipers...

But I can say this. The third smallest wire in the set is a pretty tight fit for the relief port. Based on a random amazon review , it may be about 18 thousandths of an inch. I will keep looking for my micrometer.

But I say for the moment you pick up one of those carb cleaning wire kits and just start poking the heck out of the relief port hole and see if you can clear out whatever has blocked it.

I was able to carefully poke a very small needle through the port into the cylinder which confirms that the port was actually machined - just blocked. I'll see if I can get one of those kits locally otherwise Z1Ent will be getting a call. I've got some other stuff to get from them so the postage costs US -Oz will be worthwhile.