"Using a carburetor with an overly large venturi can lead to an airstream with insufficient velocity at WOT. The insufficient velocity of the airstream means that an insufficient quantity of fuel is drawn from the main jet, and thereby to a failure to maintain the fuel/air mixture at the proper richness. Those, oversize carburetors may lead to lean WOT conditions, and thereby by to seemingly 'superior' top end performance, which ultimately, inevitably leads to seizure."
I've heard this argument at least four or five times, but I've never heard it discussed properly. An example of where it came up recently was in the "busted polinis" thread, where someone was suggesting the seizures came from "overcarburetion" (using 21mm carbs on a kit designed for 15mm carbs). What do people think of it as an argument, generally?