Brake Master Cylinder Refurbishment on A4

[Arctic Fox]

This is becoming a saga, 1st I thought my squishy brakes were just needing new fluid and bleeding, turns out this is not the case and took the opportunity to change the upper hose as well.

I'm not sure if I have a standard cylinder, its a 1975 build z900 A4 with twin front discs. The master cylinder is all metal (I've seen some that have a plastic reservoir), and an internal diameter of 14mm.

After eliciting the help of Tri-County Motorcycles to get the circlip out (thanks Keith) because my pliers didn't fit (nor did his), I discover the kit I've bought is for a bigger diameter, but listed as the correct part for year. So my questions are do I have a non-standard cylinder, and any ideas where to get a kit to sort this out?

[chrisu]

There are 2cylinders

You could the smaller cylinder used for a single disc

Is it marked 5/8?

[Arctic Fox]

Theer are no markings on it at all. I'm wonderig if its an ebay replacement part like http://www.ebay.co.uk/itm/KAWASAKI-Z650-Z900-Z1000-KH250-KH400-KH500-Z400-FRONT-BRAKE-MASTER-CYLINDER-/272778310577?hash=item3f82dab3b1:g:hXEAAOSwm8VUySKq.

Which one should it have?

[z1bman]

1/2 is for the single disc 5/8 is for twin disc if there is no markings i would say its a pattern replacement

[z1bman]

this is what you need if you cannot find a genuine one

http://www.z-power.co.uk/master-cylinder-58-double-disk


or this if you want to do front wheel stoppies

http://www.z-power.co.uk/master-cylinde ... -disk-20mm

[Arctic Fox]

Thanks, I'd come to the same conclusion after reading various guides and recommendations on the subject. It has been an education and useful to have another view on the subject.

It's kind of frustrating that a whole pattern master cylinder is not significantly more than a repair kit. Had I known that at the start I'd have saved a whole saga. I guess this is the joy of owning an older bike!

So I'll go for a 5/8" one, seems the general view is they have a bit more feel.

[z1bman]

having a single caliper brake master cylinder is probably why you have spongy brakes

[Arctic Fox]

The thought had occurred to me as well. However the whole saga started when I pulled the lever back to the twist grip. So I figured something was amiss, now if anyone wants a 12mm master cylinder with a requirement for internals......

[000zeds]

If you know a really good engineer

That master cylinder bored can be bore out to suit the bigger piston with the new kit and difference in fluid amount will not affect the brake as Kawaski offered a 2nd disc conversion for early Z1s and same small master cylinder was used but it had the larger piston

[Arctic Fox]

Well it transpires I hadn't noticed I had different levers on there as well, so having fitted the replacement cylinder and the old lever the bike stopped, but not that smartly, changing to the supplied lever and bike now stops properly.

Now I need get a aluminium clutch lever as I've got one silver one, one black one. Or get a rattle can out. But I can stop at last!