I use mobile one euro car formula
Shifts like a dream and can always find neutral. Used rosella during first 7500km, no issues there either.
I have heard negatives about amsoil in the 650s tho,can't remember what threads or site though
Best I can do. I run am soil in my snowmobile dirt bike and boat with no issues. Crank case gets rosella in crank case but sabre for pre mix