Hi, thanks for your help. appreciate. details as requested below -
Year 2000 bullet 500cc Indian import
Stock air filter (rectangular box with paper element filter)
Stock exhaust (short bottle type, I think it has a baffle)
Okay, well you have kind of a "halfway-there" kind of arrangement with a fairly decent flowing exhaust system, and a very poor-flowing intake system. This isn't the typical arrangement, so I can only give a guesstimation about it, trying to make some sort of adjustment for the plugged up intake.
I think that you should try the 27.5 pilot.
I would also use a 127.5 main.
But the critical part will be a P2 needle jet, which is not a Mikuni jet, but must come from Hitchcock's or NField Gear, or somebody who deals with either of them. Most riding comes on the needle jet, so it is responsible for most of the effects on the riding.
The pilot affects idle, and the main jet affects top speed running, but the needle jet and needle position are mostly controlling the middle throttle positions, so they are critical.
In the meantime, while waiting for the needle jet to arrive, you might try putting the needle all the way up in the richest groove on the needle.
Your current jets are too lean in all aspects.
I would strongly suggest getting rid of that OEM air filter system, and getting something at least halfway decent on there.