Indeed, after some 50 kmts the fuc.... Nut got loose. I was thinking it was something extraordinary, but for what you said now I realized is a common problem. Indeed, at Yamaha they told me that the STs report very often that problem.
The 2014 steering nut is different than previous models.
I had a really hard time trying to find the tool (bit) to tighten the nut. Besides I did not have the center stand and was hell to fix the problem. Finally a tractor mechanic had a tool a bit bigger but I managed to tighten the steering nut, but I ruined the nice aluminum nut.
The nut needs 130 newtons of torque, and I had ordered a new one. I will put some loclite on it for have tight.
What a stupid problem for a dual purpose bike.
Broadcasting from Bogotá - Colombia.