I know this much at this point:
A #78 bit shaft that measures .40mm on my crappy but very repeatable HF digital caliper will pass through the bore of a 45 pilot, & a #77 bit shaft that measures .45 will not.
The only set of 48 pilot jets that I currently have on hand are in the carbs on the bike, so this project is on hold until I can pull those jets & see if the #77 bit shaft won't pass through the bore of the 48 pilot jet.
