I do vaugely remember that, but I can't recall were I saw it either.
A really lean bottom end will get the motor machine gunning, with that very fast stacato pulsing idle. You sometimes get it on the overun from a WOT burst if you are too lean also. Guess top end being lean could cause it too, but normally the bottom.
Get your motor idling nicely, then just keep going in on the bottom end needle and eventually you will get the idle raise up into the machine gunning situation. This is as opposed to the situation where the bottom is too rich (and a large idle gap), where you will get a high steady idle that drops down as the crankcase loads up with fuel. Way lean on the bottom will result in the very fast stacato idle - quite different.
Thatīs how I have found it to occur. If anyone can add to that or correct me on things, please feel free to contribute
