BVF (as found on the original 2T bikes): stamped with BFV. Thread = 5.0mm x 0.80 (M5).
Keihin (+ clones): stamped with the 'K star' logo. Thread = 5.0mm x 0.80 (M5).
Mikuni: stamped with the 'square within a square' logo, and often an 'R'. Thread = 5.0mm x 0.75.
DellOrto: stamped with the diamond-shaped 'Inc' logo. Come in 2 sizes: 5.0mm x 0.75 & 6.0mm x 0.75 (and maybe more).
An example:
- DO big, DO small, Mikuni, BVF, Keihin org, Koso
- Top view; DE big, DE small, Mikuni, BVF, Keihin org, Koso.jpg (10.96 KiB) Viewed 33 times
- DO big, DO small, Mikuni, BVF, Keihin org, Koso
- Sideview; DE big, DE small, Mikuni, BVF, Keihin org, Koso.jpg (10.06 KiB) Viewed 33 times
Jikov tends to use M4 jets.
The flow through a jet depends on the internal diameter & length of the channel, and to a lesser extent on the taper towards that channel (both sides). And of course on the pressure differential ΔP across it, and the viscosity.
If you know more, please add.
