One problem with DIY: you don't know exactly what you have, so another size = no relationship.
With that small hole, any scratches etc. + length of hole itself (tapered entrance and exit will change when you drill) all affect flow.
Not sure at whom this is directed, but I...
- buy my own BLP or BG blanks (BG carbs use a smaller head that fits into a recess, instead of sits on top)
- have an exstensive set of drills which are measured so I know the actual sizes, not what they are supposed to be
- drill my own using an air bleed fixture on my drill press for consistency
I can't speak for any other DIYer, but I know what I have. And it is far more accurate & consistent than I have seen with some mass-produced carbs as mentioned previously.
