Since day one I’ve had the lagging thought in the back of my mind that I should replace the Clutch Slave Cylinder on the 690. Even though the stock unit has always been one of the weak parts on most any KTM, mine has always worked fine, so I’ve always thought I’d get to it later.
Returning from LAB2V 2023, I pulled into the driveway and knew I had a leak of some kind. Oil had been spewing in the area for a while. I could tell it was a slow leak, but still a leak that had to be fixed. I removed the Vanasche Case Saver which also has 2 of the three bolts that hold the slave to the case and took this picture.
There’s only four possible places the oil could be leaking from.
- The Counter Shaft Seal – which I had thought it was the last time (and it wasn’t).
- The Gear Selection Sensor – which I just sealed up before I left before LAB2V.
- The Gear Shift Seal – but the oil leak looks to be coming from above, although when it’s whipped up by the chain and wind, it could easily appear as if it’s violating gravitational laws.
- The Clutch Slave Cylinder – which honestly when we were bleeding the fluid before I left with just one of the three bolts attached could have pushed the unit away from the case and created a leak at the gasket.
So I did a really good job cleaning everything up. I found two shorter bolts so I could secure the slave to the case properly and then ran it around the block looking for leaks.
Other than gunk thrown off from my chain, there was no leaks – at all. Not from any of the four possibilities. The only thing that changed was I pulled off the Vanasche Case Saver and replaced the two bolts with proper sized ones for just the slave.
Not very scientific, but that leads me to suspect it was the slave, or more accurately, it was the gasket between the slave and case. Maybe we just didn’t torque those two bolts down enough? Maybe.
Since I had put in the new clutch pack right before LAB2V 2022 this clutch never felt like it fully released. Why? Probably just air in the line I thought. Or could it be because the new clutch was a manual Rekluse (not the fully automatic kind) that featured a bunch more plates and disks inside the same body? It wasn’t enough to cause concern and I ride pretty much without a clutch most of the time when off road.
Well, what better time to replace the stock slave with an Oberon, right? I did a little shopping around got one from Vanasche. I’ve been doing this orange and blue thing and since the Case Saver is blue I got an orange Slave to sit behind it.
A few days later the new unit arrived. I first pulled off the old slave without removing the hydraulic line. It didn’t look bad at all.
I then installed the new Oberon Slave as directed. The Oberon is built better, has tighter tolerances and uses not just plain o rings like the stock unit – but hydraulic o rings that can stand up to a lot more. I cleaned up the case surface and then oiled up the seals as directed. I mounted it to the case using the three properly sized bolts and a new gasket.
Next, I pulled the hose from the old unit, wiped it clean, and mounted it into the new unit.
I lost a lot of fluid in the process – and honestly I wasn’t hoping to keep it. There’s not a lot in volume in the system, and I might have lost it all.
I first leveled the master cylinder by turning the handlebars a certain way, and with the perch loose and twisted. With it all level, I was ready to open the master cylinder.
The fluid was still pretty clean. Not as clean as new but still pretty clean.
The Magura Master Cylinder says to use only Mineral Oil – although the Oberon unit could use either that or DOT brake fluid. I had bought a few bottles of Magura’s own mineral oil called Blood.
Assuming the line was fully empty, I started the bleed process from the lever side. Pumping slowly and refilling the reservoir constantly. Soon I could feel a little pressure and then switched to pumping the lever 6 times, opening the bleed, letting some air and fluid out, closing the bleed and then pumping again 6 times.
I think I got most of the air out but not all. The bike still doesn’t have the full clutch release I think it should. It’s time to get it right.
Putting it all together I couldn’t help but also notice that there sure was a lot of play in my lever. These are aftermarket of some kind and came with the bike. They do have an adjustment in the lever for reach but they’ve always been maxed out since I got the bike. There’s a lot of play in the pivot bolt but there’s even more play in the bolt that is above the 5 and 6! That’s not a big pivoting bolt, it’s just for the reach adjustment but it has a ton of play. And like I said before, they have always been maxed out (to the 6).
So, I’ve been looking and researching levers. I was looking at the ASV levers over on Rottweiler and they seemed like a good idea. I liked their manufacturing and style. Rott only listed a shorty C5 Billet version.
That was the only option they listed for my bike. I googled ASV and found they also sold direct and had a few options – including color! To be fair, these are not the identical levers. Rott had the C5 Billet and you can see that ASV is listing this as the F3 (F might stand for Forged?). There’s a big difference between billet and forged. But yes, I did order the blue lever with the orange adjuster.
ASV can explain the difference between the two.
These should have next to zero play in their pivots. If I like the clutch lever, I’ll probably replace the brake with the same. I don’t break levers and I like their shortys. I’ve always preferred a short lever as I am a single finger braker (and clutcher). I don’t care much about finish or warranty.
Chances are this will fix the clutch engagement issue – if it doesn’t, I look at bleeding it again.
He's an avid hockey fan, rides a mountain bike, sometimes rides a road bike, has a few motorcycles (he had a really fast one, had a big cool orange one, rode a really slow one, and is currently building a perfect "BDR Weapon"). If that isn't enough, he makes cheese and sourdough bread, loves strong beer and good red wine, and poorly plays the Mandolin.
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