yup, me and tom usually agree, and i understand your theory, but my experience totally contradicts it.
my first hopped up motor would bog after a few minutes at WOT. letting off the throttle for a few seconds, then back on it again, and the bike would take off again, only to do the same thing.
it just seemed like it was running out of fuel.
this was on a reversed jug gt4 starfire with a top speed just under 50mph.
i checked for proper fuel flow, cleaned the carb and the air filter (a dirty, oil clogged filter will make your bike bog, too.) changed plugs, changed float settings, made sure my wiring was good, and everything else possible, but the problem continued.
going back to my original hunch, i changed the petcock for one that flowed a lot better, and the problem went away. everything else was the same so that ruled out any other gremlins.
several other forum members backed me up on this, so i feel the stock petcock can't keep the NT carb at full capacity on a modified engine at WOT.
the float bowl holds a very small amount of fuel, so it's plausible that even a miniscule amount not getting the carb quick enough could cause it to bog.
i've repeated the same results on other bikes, so i believe it's been proven.
when i'm back up and riding, i'll put the stock petcock back in and prove (or disprove) it once and for all.