Modern motorcycles that are still carbureted (ex. Ninja 250 in U.S.) have "sliders" for that. The Predator was an after-market one for cars. Ford used a variable venturi in early 1990's large cars which worked well but proved problematic.
I don't know what you consider modern,but my '72 CB/CL based honda custom
hardtail is a 350 w/two carbs that have diaphragm operated slides,twisting the throttle just
controls how far they can lift.You open the blades,and vacuum strength opens the slides.
I'm not sure how far back those were in use on bikes but.....
I actually have one of the Motorcraft VV 2bbl carbs. It needs some TLC,but looks
serviceable,not sure it's worth fooling with tho'. I forget what max CFM(and at what in.Hg)
the're rated at,and I believe i read they are problematic w/any significant cams etc.
