Great news,problem solved!
I cleaned both the contacts at the TOS as well as the clutch-handle,still no luck.
But by just pure coincidence while the bike stood on the sidestand with engine running,I leaned over to look deeper into the electrical department. While doing so I rested my hand at the little metal-lip supporting the front-end of the seat,and all of a sudden the engine stopped again.
Started the motor,pushed the metal-lip,and whola! The engine stopped again!
This is the first time I managed to provoke this failure controlled,all the other times it just happened following no speciffic pattern.
I then removed all the sidepanels surrounding the tank before releasing the tank it self,and found out that the electrical connectors on top of the fuelpump was mounted at such angle (in the space between the tank itself and the part where the tank meets the seat) that when pressing that metal-lip (on the outside of the tank-cover) one of the connectors got pressed against bare metal,causing the fuelpump to quit.