I went ahead and ordered a slave cylinder rebuild kit last night. I could not locate one that had the piston included. Good idea on keeping it above the master!Rebuild kits are available for the slave cylinders. Fairly routine operation. Take pictures to remind you how it all goes together. Worst part of the job is bleeding clutch fluid after slave reassembly. Keep removed slave cylinder connected to hydraulic line if possible during overhaul and keep it above height of master cylinder. This keeps some fluid in master cylinder and hose and will help keep some of the air out during slave overhaul. You will help the bleeding process by putting small amount of correct fluid in slave before installing its piston. Bleeding these clutches once they become air bound can be a real bitch. Try pre bleeding with slave held up high above master cylinder to help remove air. I use bungee cord and zip ties to hold the bastard up from the roof rafters. The air will rise to highest point and make bleeding easier. Be sure to use correct fluid in clutch master. The cover will indicate correct fluid needed.
As for what fluid to use, I looked at the manual and it states to use DOT 5.1 fluid, which I did. Then, after seeing your (and Axzon) info, there is indeed a Magura on the master cover - and it says use mineral oil........... ah beans. If it's any consolation, I'm pretty sure a lot of the 5.1 has leaked out already into the container beneath the bike (there's a small oil leak to I need to pinpoint/correct as well eventually). I'll poke around the house to see if we have any. If not a quick trip to CVS will take care of that
Yes it does say Magura. Is that a stock piece or aftermarket? I'm guessing if it is aftermarket then the push rod would need to be longer. I have no way of figuring out if the rod is stock or modified/lengthened/aftermarket. I did notice on the rod end a few (maybe 3?) washers/spacers, so there's that. But first and foremost I need to get the cylinder leak resolved, then monkey around a bit to see how far the rod travels during a lever pull.On older KTM's the gasket thickness between the slave and the motor is important so that the slave does not put pressure on the rod that goes to the clutch while riding. The idea is to set it so that there is a small gap between the steel ball in the slave and the rod at rest (no pressure on the steel ball in the slave).
Also, if it says "Magura" on the master lid you might need to make the push rod in the master a fraction longer to get enough stroke for the slave piston to properly open the clutch plates. And the Magura text also indicates that you need to use hydraulic oil and NOT brake fluid in the master/slave!
And fit a steel bracket/cover to the slave so that if/when the rear chain comes loose/breaks it hits the bracket/cover and not the slave... That normally also cracks the left motor half... (ask me how I know...). And as your motor casings are now obsolete the extra work is worth it...
Regarding how to get the air out of the clutch: Follow Augies suggestion and hang the slave high up. Then pump the master and open the bleed nipple on the slave. Do this a few times until no more air comes out when you open the nipple.
I do have a sprocket 'guard' installed, but it's kind of beat up. I'll check out a slave cylinder cover as well.
Thank you all for the great and positive info and advice! I did go up and down the road a couple times yesterday. Shifted real good and I didn't hear anything unusual. Gonna sell one of my guitars so I can get a replacement clutch basket lol.