On thursday my clutch hydraulics gave up the ghost. Today I rebuilt the master cyl and when I took the release cyl apart I found it was pretty pitted. The problem was for sure the release cyl, it was leaking like a seive, but I'm not sure if I can get away with just replacing the seal or not since the piston and cup look somewhat worn and pitted. What do you all think?





video of the cup here: https://imgur.com/ayvyblV

I honed mine with 400 grit paper. It was some years ago so I don't remember how nasty it looked. It was nasty enough to leak. But I honed the rough stuff to smooth and clean, and put in a new seal/cup. All has been well since. You might want to try honing it to see how much needs to come off before it looks "good enough". For me, it was worth trying before looking for a new, or another, one.

That cylinder doesn't look bad at all in the picture. I would clean it up, maybe use one of those "greenie" type scouring pads. As long as there are no pits, it should be fine with a new piston and seal.

I've rebuilt worse.

I say go for it.

All you need is a new seal and lightly hone the surfaces to remove any imperfections/ridging. Smooth is the key. I think you can save that piston. If not, you might as well buy a whole new slave assembly. Rotate it so what was the bottom of the piston is now the top (the bottom suffers wear from grit collection).

In my experience, the rebuilt slave is good for a while (a year or so) but you will have to replace it eventually or keep topping up fluid as it slowly leaks down (you can do this for a long time but it's not good for the paint job or morale).

I haven't had much success with rebuilding a second time. Once the piston gets at all sloppy in the cylinder bore, it will cock and all your fluid goes bye-bye in a hurry. At that point, peace of mind is worth about the same as a new slave cylinder assembly.

So, go ahead and rebuild that bad boy and you cay say you've been there and done that.

And if you haven't trimmed away the extraneous gasket bit that keeps that area from draining properly, do that while you're at it. It will let more of the crap that collects there to escape and prolong the life of your slave.

@larolco : I think you've said it before but don't recal your answer: how long in miles do the re-built slaves last for you?

..Tom

A year or better on average. For me, that's equivalent to around 12000 kms of heavy clutch use.

I'm on my 4th or 5th slave on this bike. If I hadn't rebuilt them, I'd be nearer 7 or 8.

First was replaced under warranty when the bike was a year or two old. It's been like clockwork since then, though I have found a couple ways to delay the inevitable (trim gasket dam and drill second drain hole nearer slave). I figure I'll have to rebuild the current slave within the next year. One wrinkle is that this slave will have lived its entire life with a Tutoro chain oiler. I'm curious to see if that makes a difference. But based on when I replaced the chain a couple weeks back, the chain fling crap is just as bad with the Tutoro as it was using spray lube (Motul offroad).

It's not a big $ thing. Just one of the bike's quirks.

Some owners never have trouble with this issue. I think that's because they are not heavy clutch users and/or they don't regularly ride in shitty weather.

Okay last year I did a bit over 50,000 km and I think I did 2 slaves (I have to check my spreadsheet) so I think I"m not doing any worse than you. I keep a new one at hand all the time so I'm ready plus pack it when trips as it's easy to change.

..Tom

@iarolco: did you replace you clutch basket with realShelby's mod? I'm in the middle of doing it (wife needed me to do stuff this eve so just could do prep work and should have it installed Sunday. )

..Tom

Thanks for the tips everyone, I'll get the parts and then grab another slave cylinder when this one starts leaking again. It was gross inside from sticky chain lube, I ride in traffic a bunch and when I'm not in traffic it's usually trails so my clutch gets used a lot.

The gasket to trim is 27A on the parts fiche? Where do you drill the hole?

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I think he is talking about the gasket that is within the front sprocket area at the bottom, not part of the slave cylinder.

..Tom