Saw this in an old Street Chopper the other day.
It was a 400 4 being roadraced, they built a plenum manifold and mounted a Branch Mikuni 2 throat..likks like a mini Weber.
The manifold had straight runners ending in a rectangular plenum, at least the width as the runners, ie 1 1/4 x 2 3/4, narrow part at the top (those are only approx measurements, taken off magazine page by eyecrometer!).
Anyway in the pic he was running stacks, and claimed a 9 hp gain over the other carbs!!.. quite a bit on a 400 ! I bet it pulled hard thru the midrange, those types of carbs can give fantastic response..
FWIW, may help someone or be a nice project..
