I decided to change the bars on my W800 to a set of light weight alloy bars. The bar end mirrors I used have expanding sleeves to hold them in place. Push them into the bar and tighten the bolt to lock them in place.
Here is a run down of how to change the bars.
1. Lift the rubber boot on both mirrors and remove them.
2. Remove both bolts on the left and right lever clamps.
3. Remove both screws under the left and right controls and remove the controls.
4. Remove both grips from the bars.
5. Remove the 4 bolts holding the bars in place.
6. Mark a spot on the new bars to drill to align the controls.
7. Reverse above steps to fit new bars.
8. Slide bar end mirrors into the bars and tighten bolt to expand the spacer/sleeve to hold them in place.
9. Enjoy your new bars and mirrors.
Hope that helps some what Michiel.
Let me know if you need more details.