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Just an FYI. When the slave cylinder starts to leak at the plunger, all it requires is a new buna-n rubber o-ring, available at any/all hydraulic shops. It's a .21 cent piece. Screw KTM and their unwillingness to sell just the o-ring instead of the whole $140+ slave cylinder.
Good to know.
I haven't taken mine apart yet, or even bled it, but great to hear that it's serviceable. :thumbup:
 

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Just an FYI. When the slave cylinder starts to leak at the plunger, all it requires is a new buna-n rubber o-ring, available at any/all hydraulic shops. It's a .21 cent piece. Screw KTM and their unwillingness to sell just the o-ring instead of the whole $140+ slave cylinder.
Do you know the size?
 

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I have a bag of them at home. Let me look tonight when I get home, but if memory serves me right, its a #20. But let me confirm.
 

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I'm a little noobish when it comes to hydraulic components, but are all #20 o-rings the same? Are we sure the required material is buna-n?

I've been looking into normal magura clutch issues for a long time, and this information is kind of a breakthrough.
 

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I'm a little noobish when it comes to hydraulic components, but are all #20 o-rings the same? Are we sure the required material is buna-n?

I've been looking into normal magura clutch issues for a long time, and this information is kind of a breakthrough.
Buna-N is just a very very resistant material to fuel and oil. It should be more than plenty for the application. And yes, all #20 o-rings should be the same, atleast here in the states.
 

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Buna-N was described as overkill for a mineral oil based application, but I don't want to be stranded again without a functional clutch due to it not being able to survive occasional contact with fuel/oil.
 

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Ancient posts but WHOEVER was suggesting cross contamination between ENGINE OIL and brake fluid??? WTF??? That is basically IMPOSSIBLE unless some moron mixes up containers! Which WTF might as well mix-up catsup with brake fluid....SERIOUSLY?? What is WRONG with some of these dudes??
 

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Thanks to this forum. I learned all the info here myself for my '07 690 SM.

Well, if you are driving along and all of a sudden your clutch is gone, then you open the top master cylinder and there's nothing there with no signs of leakage elsewhere, that means your slave is blown and mineral oil is in your engine.

There is no short term damage from this, but oil loaded with mineral oil causes notchy shifting and a weird feeling clutch. Long term, if you don't change your oil right away you could wreck your engine. Most people resolve the problem right away, but the wrong thing to do would be to refill and bleed the mineral oil and go on your merry way without an oil change.

Your slave could be partially gone with no serious symptoms yet other than a low level and bubbles in the line. Leakage can go both ways and engine oil can get in your mineral oil. Take a look - if it's very dark and it smells like combustible products, it could be on it's way to failure. likewise, if the level in the top cylinder is low, you've probably leaked a good portion of it into the oil.

There are 3 ways to bleed the system. 1)from the top, pumping it through with clutch action and bleeding out the valve at the bottom into a catch pot; 2)vacuuming it out through the bottom with the kit syringe through the bleed valve, and 3)pressurized from the bottom up with the kit syringe through the valve. The old fluid is removed with the other syringe at the top cylinder or just soaked up with a rag. Some like one way better than other ways but I like #3 because it has the best chance to get bubbles out of the system. My local KTM dealer recommends #3. I think the bleeding kit recommends #2. #1 might work and is easiest but it can be hard to get bubbles out this way.

The only real problem with #3 is that if you don't have the valve opened up far enough, the pressure makes the mineral oil explode in your face. Ask me how I know, heheh. The dealer even warned me about it.

The key to making these slave cylinders last is to bleed every 1500 miles or so. there may be some other tips to be found on the forum, I know there are tons of posts on the subject. Google search helps more than the in-forum search.

Seems like kind of a pain but when these Magura clutches work well, there is no beating them for feel.
Thanks to this forum. I learned all the info here myself for my '07 690 SM.

Well, if you are driving along and all of a sudden your clutch is gone, then you open the top master cylinder and there's nothing there with no signs of leakage elsewhere, that means your slave is blown and mineral oil is in your engine.

There is no short term damage from this, but oil loaded with mineral oil causes notchy shifting and a weird feeling clutch. Long term, if you don't change your oil right away you could wreck your engine. Most people resolve the problem right away, but the wrong thing to do would be to refill and bleed the mineral oil and go on your merry way without an oil change.

Your slave could be partially gone with no serious symptoms yet other than a low level and bubbles in the line. Leakage can go both ways and engine oil can get in your mineral oil. Take a look - if it's very dark and it smells like combustible products, it could be on it's way to failure. likewise, if the level in the top cylinder is low, you've probably leaked a good portion of it into the oil.

There are 3 ways to bleed the system. 1)from the top, pumping it through with clutch action and bleeding out the valve at the bottom into a catch pot; 2)vacuuming it out through the bottom with the kit syringe through the bleed valve, and 3)pressurized from the bottom up with the kit syringe through the valve. The old fluid is removed with the other syringe at the top cylinder or just soaked up with a rag. Some like one way better than other ways but I like #3 because it has the best chance to get bubbles out of the system. My local KTM dealer recommends #3. I think the bleeding kit recommends #2. #1 might work and is easiest but it can be hard to get bubbles out this way.

The only real problem with #3 is that if you don't have the valve opened up far enough, the pressure makes the mineral oil explode in your face. Ask me how I know, heheh. The dealer even warned me about it.

The key to making these slave cylinders last is to bleed every 1500 miles or so. there may be some other tips to be found on the forum, I know there are tons of posts on the subject. Google search helps more than the in-forum search.

Seems like kind of a pain but when these Magura clutches work well, there is no beating them for feel.
 

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Ancient posts but WHOEVER was suggesting cross contamination between ENGINE OIL and brake fluid??? WTF??? That is basically IMPOSSIBLE unless some moron mixes up containers! Which WTF might as well mix-up catsup with brake fluid....SERIOUSLY?? What is WRONG with some of these dudes??
You idiot. Do you see anyone in this thread talking about brake fluid? You just made a total ass of yourself.

CLUTCH. The 690 has a mineral oil clutch that connects to the engine case and has some o-ring seals that have been known to lose their seal and dump the mineral oil into the case.

Welcome to the forum BTW. Great 1st post. Lol.
 

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You idiot. Do you see anyone in this thread talking about brake fluid? You just made a total ass of yourself.

CLUTCH. The 690 has a mineral oil clutch that connects to the engine case and has some o-ring seals that have been known to lose their seal and dump the mineral oil into the case.

Welcome to the forum BTW. Great 1st post. Lol.
Excellent takedown. That said, for those finding this thread now that it's been kicked back up to the top, here we are in 2021 and the KTM Magura slave cylinders are still terrible.

And now they in fact do use brake fluid instead of the mineral oil of the past. So you totally can cross-contaminate your engine oil with brake fluid, making the poster a couple up doubly wrong.
 

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Excellent takedown. That said, for those finding this thread now that it's been kicked back up to the top, here we are in 2021 and the KTM Magura slave cylinders are still terrible.

And now they in fact do use brake fluid instead of the mineral oil of the past. So you totally can cross-contaminate your engine oil with brake fluid, making the poster a couple up doubly wrong.
Oh wow they actually use brake fluid now? What year did that start? I can kind of see the benefit - the Magura Blood was somewhat affected by temperature and in cold weather the clutch would feel sluggish. I bet that goes away with brake fluid.

It's all a pain in the ass but when it works, it feels soo good. One of the best clutches I've ever pulled. The whole 690 was like that. I always said that bike was like a supermodel, what a bitch to live with but she sure was fun in the saddle.
 

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Oh wow they actually use brake fluid now? What year did that start? I can kind of see the benefit - the Magura Blood was somewhat affected by temperature and in cold weather the clutch would feel sluggish. I bet that goes away with brake fluid.
I believe the SMC-R switched over to DOT4/5.1 in 2019 when they reintroduced the model to the lineup. From what I can see, KTMs in general switched by 2018.
 
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