I don't know about the Quad lock in particular, but I've got my Ram X-Mount attached to the fork stem hole of my 2021 Ninja 650 with one of these guys:
https://smile.amazon.com/gp/product/B00M0T1WTM/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
It fits perfectly and is rock solid.
Does this model year have the hexagonal hole in the center of the steering tube mount? I am using this mount on my 2018 Ninja 650 and it is a thing of beauty-- way better than any of the Ram or Quadlock options I've found for this particular model.
Edit: I know it says for TomTom in the description for the item, but really it just has a 1" Ram ball mount so you can use whatever mount on top of it you want. I use a Quadlock phone case with a short Ram extension arm.
I am using this thing combined with a RAM connector and RAM phone mount.
Also on a 2018 Ninja 650, no problems so far.