KTM  + other Hydraulic brakes / systems sometimes require a special knack to remove the air from the fluid.  Without the air extracted from the brakes, they will feel spongey and not work properly. Its luck of the draw if they will bleed first time or you can be unlucky and it take thre or four attempts.

Before you start, make sure you have the correct TYPE of Brake or clutch Fluid as this is becoming more of an issue as different type of brake and clutch fluid's advances. Don't take for granted what is written or cast on to the top of the cap as certain brembo or magura systems may use other types of fluid from bike models / manufacture or application.

To overcome this the our recommended procedure is......

If you studied Physic's at school then you will understand that any Air or Bubbles in a hydraulic system will not allow the build up of pressure. The trick here is to force or encourage the air to go UPHILL when bleeding via;

a: Holding the caliper up above the master cyclinder so any traped air will travel easyier up the hose rather down it.

b: Put an sufficient amount of correct fluid in a syringe and via a piece of rubber pipe, crack open the bleed nipple and force upwards enough fluid to make sure that all the air is expelled from the full system out of the top of the master cylinder. Make sure that the top is off the master cyclinder (carefull the excess fluid is caught via a rag of dish etc) and that also the any lever / adjuster screw is backed off all the way to allow the piston to fully return. 

If the system is guarenteed free of air and the brake or hydraulic clutch still does not create pressure, then we suggest from our expierence, that you change the seal kit in the master cyclinder housing and try again.

some rear brake systems on KTM's had a weak seal fitted to the rear brake master cyclinder around '05-'07 which gave an inconsistant brake pressure. When applied the pedal gave some initial pressure, but then slowly continued down.  A single seal replacement will cure this problem.