I just went through a $100 lesson I thought I'd pass on in the hopes of helping some other KTM owner the mistake.
I was back-bleeding my clutch system last night, and went to button everything back up. I put the bleeder valve back on, replacing the fitting for the Magura kit, and tightened it up. The oil kept coming out the bleed hole - ugh! Several tries later, I realized I was hosed. I went to bed, resisting the temptation to re-model my bike with a hammer.
I pulled off the slave cylinder with cooler temperment (and a new slave cylinder ready). I found that the Magura bleeder fitting had a damaged thread, which caused ALL of the threads in the cylinder to get buggered up. Now when I put this on, it seemed really easy, so what gives? Anyway, I cleaned it up with an M8x1.0 die and put the new cylinder back on.
Moral of the story is be really careful with threading the back-bleed kit fitting onto the clutch slave cylinder!