front master Leaking...

So this all started when I decided to replace the seals in my front brake callipers(currently not leaking).
I also decided to clean out the front master cylinder as it had some red gunk in it. upon trying to bleed the system the brake lever wouldn't get to that rock solid feel that it had before.

I decided then that the piston must be damaged and ordered a rebuild kit off of E bay. upon installing the kit it still leaks but only when the lever is applied. The bore has some red corrosion but no serious pitting from what I could see.

Does anyone have any tips for getting he piston to seal, I have looked at honing the bore but am unsure how to go about it.
I can upload pictures if that would help.

What leaks and from where?

The piston and from the bottom of the dust seal

If I understand you correctly, the master cylinder did not leak until you put a rebuild kit in? Well, that's often the case with these rebuild kits. Why not just put the old parts back in that didn't leak?

That was the case originally before I cleaned it. After it leaked.

Ok So i took some photos. What do you think still usable?

You need to hone that bore out, that's why it's leaking.

Heh. No, that thing looks like it sank with the Titanic. Must have had lots of water in the fluid for a long time. You're going to have to at least soak it in acid or something to get all that corrosion off, and the bore is never going to be the same again. I think a new master cylinder would be cheaper than a hone and your time, so in this case I'd just get a "new" one if I were you.

You might be able to lightly hone it, but that looks pretty bad. I wouldn't use acid.

They can be reconditioned with an insert fitted.

Those front master cylinders are fitted to a lot of the kz fours. If you replace with another then make sure the cylinder bore is the same, I think 5/8.

Does anyone have any good methods for lightly honing it?

razmo99 wrote: Does anyone have any good methods for lightly honing it?

Well you could either buy a proper hone of the appropriate size (but this will be a good fraction of the cost of a "new" master cylinder), or you could try to improvise something. Perhaps a giant cotton swab (in think there are some cylindrical ones in dremel kits which would be around the right size (although with too short a shaft) and some Mother's Aluminum Polish. Mother's is pretty good at getting corrosion off aluminum--you might be able to get it mostly smooth with some on a rolled up paper towel.

No eBay APP ID and/or Cert ID defined in Kunena configurationAnother option would be to just buy a new one, 8 yrs. ago when my front M/C started leaking I started looking for a rebuild kit & they were around 39.00, & I ran across this place & for 49.00 I bought a brand new M/C with free shipping, I haven't had any problems with it in 8 yrs. I don't know if it would be free shipping to Australia, but you could ask
& new always looks better than old,
Pete