all they're doing is richening up the idle jet. the idle jet is the small tube in the primary cluster. i do this a bunch and is a major help on factory avs's. in short go to .035" on the 600cfm carbs and somewhere between .037"-.040" on the 750's and 800's. i never use large squirters on anything i drive; they don't work. i do use the tan colored accelerator pumps exclusively. also look for casting flash in the groove that feeds the pump reservoir. simple stuff.

i'm going to add something else. i've found dealing with the 800avs (not the avs2) that taking fuel out does help them drive better off idle. they have a .040" idle jet and don't go bigger. i've reduced main metering jet area and used small squirters to improve tip-in.