Weber idle jet adjustment

[Neil8p]

Following on from "a shove in the right direction", the weber tuning manual states I can make the progression mixture weaker by reducing the fuel jet diameter or by increasing the air jet diameter.

Makes sense, but which is the best one to change - fuel or air?

The idle jets are currently 50 F9 and if it helps, the rest of the setup is as follows - venturi 30mm, air corrector 160, emulsion tube F11 and main jet 125

Cheers

Neil