Spongy front brake - Can each component be tested?

[Rich]

Kiwi,
I am sure you will have thought about this, but you are not using silicone brake fluid are you. Its supposed to be non hygroscopic ie does not absorb water and it does not strip paint like normal brake fluid BUt its more compressible apparently and when I tried it on my old z1 a few years ago it made the brakes horrible and spongy. Just thought i would mention it on the off chance.
good luck.

and if you do you should also change all the seals.

[kiwiz]

Steve,
the fluid I have been using is glycol based Dot 4.

My J has at some point been in a pretty significant prang. Someone suggested to me that the mastercylinder might not be the original for the bike! As a result the bore stroke combination might not be appropriate for the two caliper set up. There does seem to be a lot of travel in the lever before anything bites.

Though the MC looks like the original is there any way of telling whether this could be off another model Kawasaki?

I have now got a new piston and seals to completely overhaul the caliper that was completely untouched and seals to do the other caliper which had the piston replaced a few years ago. If thats not it I may look at the suggestion made by Sorf near the beggining of this thread of using some sort of threaded adjuster to reduce lever clearance.

[chrisNI]

It doesn't really matter what model it's off but it should be a 5/8" master cylinder to work with the double disks, the single disk ones were smaller. It should be stamped on the underside.