Ok,
I've been obsessing over my last purchases to get ready for the Nelson GTG. I went to Austin today for ROT (Republic of Texas) rally and stopped by the Kury trucks and met Greg Dischler from BagTec (Bagtec is the OEM for Kury bags).. Greg is the designer and patent holder of most of the bags there. I had brought my scoot over and had the 4142 bag and told him I was thinking about using it when he said no way -- use the 4144 and took the darned 4142 out of my hand and said "you don't want this"....
He grabbed the 4144 (it is the same price as the 4142 but 15% larger) and proceeded to mount it up on the scoot -- it took all of 2 minutes, fit perfect, and looks great. Lots of D-rings for tying down jackets etc.
I mentioned in passing that I wondered if the Grand Touring would fit and he said NO WAY, only fits on Standard size rack.
If you still need a rack bag you might consider the Kury 4144...
Mark