Cutaway refers to the shape of the slide which has a section of its cylindrical shape "cut a way". For many carb types changing the cutaway is an option and is a way of fine tuning the carbs (throttle settings between the idle circuit domination and needle clip position). You can basically buy richer or leaner slides (cutaway changes) In theory this would also be the case with our stock 750 carbs but as far as I know there are no current suppliers of different slides. Modifying with a grinder and welder might be an option but most people are unaware and ignore this area of carb tuning. For our purposes, adjusting idle mix (perhaps swaping idle jets) adjusting needle clip position (as with slides needles with different tapers are available for some carbs but not ours) and main jet size are the easy options for carb tuning . . . . .