Ok here's the scoop, Seems that Factory Pro for some unknown reason desided to toss around the name emulsion tube in place of the proper name needle jet.
Not necesarily, the name Emulsion tube has been around along time and is taught in many mechanic schools and is in many books ( shop manual or service manual)
Here are some more confusing terms : petcock, fuel switch, pilot jet, slow jet, air screw , fuel screw, air/fuel screw, tachometer, rev counter, piston clip, jesus clip, rim, wheel, disc, rotor, gas, fuel, ignition switch, ignition kill switch, enrichner, choke, ignitor, pickup, coil, cdi, spark box, ect...