Carb tuning, larger accelerator pump nozzle?
I’ve had a bit of time to actually sit down and think about the MAB and what it does. The only time I can think of when the MAB won’t start the mains earlier is if yo have a huge kill bleed or some other issue like that. Why you would have a big kill bleed I can’t say. But it would be one reason. The reason the MAB initiates the mains starting earlier is the pressure difference between the MAB and the fuel nozzle. That all by itself makes the mains start quicker. With the added air of the bigger MAB, you also change the viscosity of the fuel in the main well. You make the fuel less viscous with more air. A less viscous fuel/air mixture moves easier, so that initiates fuel flow sooner. It’s as simple as that. Anything else is attributable bad tuning decisions elsewhere in the carb.