Emulsion tube / needle jet holder for the Honda CB350F and CB400F. These are no longer available from Honda. This is the long tube that fits around the needle jet, as the slide rises and lifts the needle, more holes on the emulsion tube are exposed, thus more fuel is available for atomization. If those holes are plugged, or if the tube has been damaged, the engine won't run right above 1,200 rpm. It's listed in the parts fiche as part of the "Needle Jet Set." Be careful when removing or installing the emulsion tube, use a tool that is softer than brass to avoid damaging it.
It is common for these to be stuck in the carburetor. If they need to be cleaned, the safest way to get them out, if they're really stuck, is to remove the slides and use a punch the same size as the outer diameter of the emulsion tube (ideally this punch should be brass or a softer material). Slowly tap out the tube from the top of the carb.
Overall Length: 37mm
Outer Diameter: 5.7mm
Honda Part Number: 16012-377-004 (Needle Jet Set - Only the emulsion tube in included)
CB350F Four - 1972-1974
CB400F Super Sport - 1975-1977