You are able to do this without removing too much. I only had to remove the seat, the plastic shrouds and then the tank. That pretty much gets you to the top of the motor. From there I was able to remove the lid on the motor. It is kind of a puzzle trying to get the lid out of the frame but it will come out.
Once the lid was off I made sure the piston was at top dead center by taking off the Silver plug and Black plastic cap on the left side of the motor. (I will try to get pictures of this if need be) This process is pretty much the same as any other bike. You will need to line up the line on the rotor to the point on the case. You also need to make sure the cams are lined up by looking at the lines etched in them.
Once everything was at TDC I was able to measure the intake clearances with a standard set of feeler gauges by sliding them between the Cam shaft and the rocker arm. The exhaust valves were a little harder to get too and I ended up loosening the radiator to get the room I needed to measure these. Like I said before all four of my valves were out of spec, so I needed to replace them all.
*Side note the shims are 10mm in diameter*
Replacing them will be another post if it is needed. Hopefully you don’t need too. My buddy checked his KTM Duke the same time I checked my Vitpilen and all four of his valves were fine. So I think it is hit or miss.
Hopefully this helps.
The only Special tools that I needed are a set of feeler gauges, torque wrench, and calipers.