I’ve been researching something similar. One thing I’ve noticed across the various cable lengths that are available, they all provide 2.25-2.5” of stroke at the throttle arm when the jacket sleeve is clamped in the correct position.

If you position the jacket under the clamp so that you have 2.25 of stroke at the throttle arm, does that change anything?

If you have to clamp on the plastic portion of the jacket to get 2.25 then something is amiss…..but you knew that.