TOPIC:

Trying to grasp the needle-clip position relationship between two Main Jet sizes.

Do I have a 115 when the clip is in the top slot, and a 117.5 with the clip in the bottom slot, and essentially a 116.25 if the clip is in the middle?

It's mainly for altitude changes. I doubt it would cover that large a jump just like the pilot air screw. I think you'd have better luck with the main air/bleed jets.
Steve

The size of the main is the size of the main, nothing will change that.
The needle is a metering device and the taper controls the rate of fuel feed at a particular throttle opening.
Lifting or lowering the needle only allows small changes to increase or decrease that feed to fine tune the mix.

Not sure if this will help or not but here is a page from a mikuni carb manual that shows the change in fuel flow between the slots.

Very helpful information guy's. I think my jetting is close, if not dead on for the present cool weather conditions.
Amazing how one minuscule jetting change can detrimentally alter things.