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Discussion Starter · #1 · (Edited)
Hey hey everybody! Been out riding a lot. Just a quick update because reasons lol

- I have not replaced the loose spokes yet. There's 4 of em on the rear. I'm debating on just replacing the 4 or getting a whole set. I'm inclined to just replace the 4 as I dont want an out of center wheel after replacing all of em lol. Since the tire has to come off, is it prudent to get a new tube and ............ uhhhhhh.........whatever that strip of rubberlike stuff that covers the inside of the rim?

- I definitely have a leak in the clutch system! Two days ago the clutch basically disappeared after about an hour ride. I could pump it up about 10 times and it would work for a minute. Opened the reservoir cover and hardly any fluid 🤦‍♂️. Yesterday I filled it up, pumped the lever about a hundred times till no bubbles came out. What bubbles did come out were very very tiny. About an hour into the ride the same thing - hardly any clutch. Again the reservoir was empty! I'm not seeing any obvious signs of leakage. I'll take off the slave cylinder guard today for a closer look-see. I'll wipe down/dry any suspect areas then fill it up with fluid again, pump the lever and come back in an hour or so for inspection. I did rebuild the slave cylinder earlier, but who knows. Possibly an oil seal? My buddy said check the oil to see if it's any higher, but since the reservoir is so small it would be next to impossible to notice such a small increase. Thankfully it's mineral oil and not hydraulic fluid in there!

- Been having tons of fun riding up in the woods. My buddy takes his XR250 and we have a good old time going on both logging roads and tight trails! It can be a bit of a challenge on some of the more twisty stuff but it's all good. I've missed the days where I would do this almost every day (almost 25 yrs ago lol)

- Definitely getting fork seals so that will be a winter project. Much warmer in the basement than the garage!

That's it for now. Keep the shiny side up!

Edit:
The more I think about it, the more I think there isn't an 'oil seal' per se other than the O-ring for the slave cylinder.

for reference: #69 listed on this picture. I have replaced it already:

1998 125 Clutch diagram

What are some other potential points for leakage/failure?
  • Master cylinder - no leakage seen
  • Hydraulic line itself - I haven't checked the entire length of the line for pinholes or leaks. I reckon I can take off the tank and take a look-see
  • The 'bleeder' bolt/crush washers area (#68)
  • Slave cylinder gasket (#65)
  • O-ring (#69)
  • Push Rod (#53). I dont remember exactly what it goes thru, but it looks like a lot of things (maybe #13, #1, #95, maybe more - I can't remember)

Fortunately I (think) I can source tons of different size O-rings at the local Ace Hardware - hooray!

OK, I've rambled on long enough. That's what I get for eating Popsicles at 9pm!
 

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In your diagram the piston in the slave is missing... part #69 here in a 2013 125 parts diagram: 2013 KTM 125 SX Clutch | KTM World . That one has the O-ring fitted to it. Regarding fluid for the clutch: Today brake fluid is used in the KTM clutch. There was a period KTM used the Magura clutch master/slave set-up. That one used hydraulic oil.

If there are no leaks at the master or the hydraulic line, then the culprit will be the slave piston and it's O-ring.

Could also be wear in the pushrod (shorter pushrod means the slave piston has to come out further and possibly leak out the clutch fluid...

In the older KTM's the gasket/s under the slave was used to adjust the freeplay in the clutch. Too thin and the clutch will slip. Too thick and the clutch plates will not open enough for a smooth working clutch, and this could also result in piston going to far out and allowing the clutch fluid to leak in to the engine.

Another possibility is that, if you still have the original slave, there is too much wear in the slave and the clutch fluid passes by the piston seal (O-ring).
 

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Discussion Starter · #3 ·
In your diagram the piston in the slave is missing... part #69 here in a 2013 125 parts diagram: 2013 KTM 125 SX Clutch | KTM World . That one has the O-ring fitted to it. Regarding fluid for the clutch: Today brake fluid is used in the KTM clutch. There was a period KTM used the Magura clutch master/slave set-up. That one used hydraulic oil.

If there are no leaks at the master or the hydraulic line, then the culprit will be the slave piston and it's O-ring.

Could also be wear in the pushrod (shorter pushrod means the slave piston has to come out further and possibly leak out the clutch fluid...

In the older KTM's the gasket/s under the slave was used to adjust the freeplay in the clutch. Too thin and the clutch will slip. Too thick and the clutch plates will not open enough for a smooth working clutch, and this could also result in piston going to far out and allowing the clutch fluid to leak in to the engine.

Another possibility is that, if you still have the original slave, there is too much wear in the slave and the clutch fluid passes by the piston seal (O-ring).

Yeah, I couldn't find the actual piston anywhere. Thanks for finding that! I tore the slave cylinder assembly apart yesterday and cleaned it up real good. I had used gasket maker to 'hold' the gasket to allow for easier assembly. This time I didn't use any (I cleaned off as much gasket maker as I could from the original gasket and reused it). I'm thinking maybe the extra distance (no matter how small it is) would affect the pushrod throw in a bad way.

Anyhow, tossed a new o-ring in there too since I had some new ones. After tossing it back together I tried to reverse bleed it using a syringe. As before I couldn't get any mineral oil to travel up thru the line to the master cylinder resevoir. I removed the 'bleeder bolt' (number 62 on either diagram) and cleaned it out real good. Air flow is good thru the bottom going out the 2 tiny holes in the bolt itself. I thought the top part (nipple?) would ( I think?) be where you attach the syringe to backbleed it, but there's no way for fluid to travel thru. Either it's just for looks for it's badly blocked shrugs

At any rate, after re-assembly and bleeding (clutch lever + tightening/loosening the bolt), I looked down and found out I forgot the put the little spring that goes in the back of the piston......argh! Back apart, put the spring in, get mineral oil everywhere lol. Got it back together and bled. I pumped up the lever, put a clean paper towel under the slave cylinder for easier leak detection, and left it overnight. I have not gone back out to look but am hopeful there will be no leakage. It's supposed to rain the next 3 days so a ride will have to wait.

Thank you for replying and the great info Axzon!
 

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Yep it does 👍
OK... then there is one more thing that we need to cover: As the Magura master cylinder gets worn the stroke the standard handle/leaver can give you is not enough anymore. You can adjust the handle/leaver and fit a rebuild kit, but in the end it is not enough. There is a pin that connects the handle/leaver to the piston (the pin goes in to the piston). We replaced that one with a longer one made from a s/s spoke and we had a well working clutch master again. This pin is not seen in the parts diagram as it goes in to the piston.
 

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Discussion Starter · #7 ·
OK... then there is one more thing that we need to cover: As the Magura master cylinder gets worn the stroke the standard handle/leaver can give you is not enough anymore. You can adjust the handle/leaver and fit a rebuild kit, but in the end it is not enough. There is a pin that connects the handle/leaver to the piston (the pin goes in to the piston). We replaced that one with a longer one made from a s/s spoke and we had a well working clutch master again. This pin is not seen in the parts diagram as it goes in to the piston.
I think you mean this?




pics are with the pin adjuster all the way in (clockwise) and all the way out (counter clockwise)
There’s about 1/2” (13mm) free play with it all the way in before it feels like the clutch starts to engage. With it all the way out the lever moves in by itself (as in the picture seen by the gap between the lever and the holder/bracket)
Perhaps a longer pin is in order. I hadn’t thought of that. I reckon I can figure out the pin travel as it is now and then find the max travel using something (like a spoke) and see how big the delta is.
Kudos Axzon for thinking outside the box! 👍
 

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I think you mean this?

View attachment 110186
View attachment 110187

pics are with the pin adjuster all the way in (clockwise) and all the way out (counter clockwise)
There’s about 1/2” (13mm) free play with it all the way in before it feels like the clutch starts to engage. With it all the way out the lever moves in by itself (as in the picture seen by the gap between the lever and the holder/bracket)
Perhaps a longer pin is in order. I hadn’t thought of that. I reckon I can figure out the pin travel as it is now and then find the max travel using something (like a spoke) and see how big the delta is.
Kudos Axzon for thinking outside the box! 👍
You can make a longer adjustable one, that seems to work also at times. But I am talking about a pin that goes in to the piston. (Will become obvious when you see it). I have done this on two of ours and that solved the issue. I explained it to another member on here but he could not find the pin I was talking about... and as the parts break-down of the master is very poor it does not show up (as the pin is part of the piston). At the same time there is always a chance that Magura made a change and the pin I am talking about is no more there... In that case by drilling a hole in the piston for a pin (made out of a spoke) would also solve it. And by doing that you can then cut a few different length of spokes to set the "home" position and again get adjustment from the red knob!
 

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Discussion Starter · #9 ·
You can make a longer adjustable one, that seems to work also at times. But I am talking about a pin that goes in to the piston. (Will become obvious when you see it). I have done this on two of ours and that solved the issue. I explained it to another member on here but he could not find the pin I was talking about... and as the parts break-down of the master is very poor it does not show up (as the pin is part of the piston). At the same time there is always a chance that Magura made a change and the pin I am talking about is no more there... In that case by drilling a hole in the piston for a pin (made out of a spoke) would also solve it. And by doing that you can then cut a few different length of spokes to set the "home" position and again get adjustment from the red knob!
Oh ok gotcha! Good to know (y) So far the clutch seems to have normal pressure. I haven't ridden in a while due to weather/other commitments, but hope to soon!

About the spokes - I think I'll order a whole set instead of just a few, but just replace the ones that need replaced. I neglected to take into account there seem to be 7 different 'bends' for the rear wheel spokes. So I'll just order a whole set to cover my bases :)

I think I found some from Moose Racing here:

Amazon.com: Moose Racing Spoke Kit - 19"/Silver : Automotive

The color indicates 'silver'. They also have a 'chrome' plating too, but mine are stainless, so I think 'silver' is the correct finish. What do y'all think? Seems like they're unavailable on a lot of sites :(

Oh, here are some pics of the rim/spokes too, just because I went out and took a few lol. I'm guessing the '19' on the rim indicates the size. I'll also order a tube and 'rim strip' since I'll be taking the tire off.

Hope you're all doin good out there!


 

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Oh ok gotcha! Good to know (y) So far the clutch seems to have normal pressure. I haven't ridden in a while due to weather/other commitments, but hope to soon!

About the spokes - I think I'll order a whole set instead of just a few, but just replace the ones that need replaced. I neglected to take into account there seem to be 7 different 'bends' for the rear wheel spokes. So I'll just order a whole set to cover my bases :)

I think I found some from Moose Racing here:

Amazon.com: Moose Racing Spoke Kit - 19"/Silver : Automotive

The color indicates 'silver'. They also have a 'chrome' plating too, but mine are stainless, so I think 'silver' is the correct finish. What do y'all think? Seems like they're unavailable on a lot of sites :(

Oh, here are some pics of the rim/spokes too, just because I went out and took a few lol. I'm guessing the '19' on the rim indicates the size. I'll also order a tube and 'rim strip' since I'll be taking the tire off.

Hope you're all doin good out there!

View attachment 110290
View attachment 110289
Yep, 19" is the rim size (and it takes a 19" tyre)
 
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