ETZ250 Master cylinder inner piston seal.

[Blurredman]

Hi guys,

My lever on my etz250 original brake master cylinder slowly sinks to the bars. No leaks, so my feeling is that the inner seal on the piston is split or broken. It's kinda usable still as if you pull the lever tighter than biting point the brake is still operational and solid, however it is obviously not ideal..

It's a funny looking seal however- has anyone got a good souce (Uk based, and just for the seal alone..) for the seal, or equivelent I can find on e-Bay or something?


Many thanks..


Matt

[Puffs]

Yes, maybe some fraying on a seal edge, but also look at the bore.

Sorry, no advice on a local source.

[parrbd]

The best fix is to get a Japanese master cylinder from the wreckers. Any 1/2" master cylinder will work, you just need to get a new hose, which it is probably due for anyway.
'

[Blurredman]

I rebuilt this master cylinder about three years ago, indeed with a new piston/seal/rubbers kit etc. Flexi-pipe itself isn't old either.

I don't want to buy another kit esspecially when only one item is required. Initially I did have the replace the outter seal as that failed after only a few months but a replacement outter seal (standard oil seal type) has worked fine for years. Infact it was only after I did a bi-annual brake fluid replacement recently which has seemingly created this prooblem.


I do have a Gilera DNA 50cc master cylinder on my 251, and it's good for the application, cheap and easy to get replacement levers too, but I would rather just replace the seal in the faulty unit.



I suspect part 5 in this parts diagramme:

[dave47]

Its listed on themzshop website. I've bought them in the past but can't remember where from. You might need the big outer seal as well as its likely to be damaged getting it out.

[Blurredman]

Dave, I purchased 2x inner seals from the MZ shop and I have installed one last night.


Brakes feel good! Also gave the whole system a good clean out, and yes I did replace the outter one too. Also replaced bleed screw as the original one was rounded a bit.


Have yet to use the bike on the road... but it's fixed! I wonder for how long?