Sorry it was late allready and too dark but I found out a bit more. I adjusted the choke flap according to the manual but the engine still was stalling after about 30 seconds. I started it again and when the rpms started going down I closed the flap a bit by hand. The engine was immediately running better then. So as I see it the choke can (don't know how I should call it. The black round thing which pulls the choke open by a bimetallic spring when it gets hot) pulls the choke flap open too fast.
I'm going to try and adjust it a bit tomorrow. unfortunately I only have one try per evening because the engine has to be cold. I'm a bit worried I won't be able to adjust it enough because at one point it won't be able to pull the flap open enough for the normal running hot engine.
