Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 290Get this manual
2Starting Enrichment (SE) SYSTEM This engine is equipped with the new system of the Manual Starting Enrichment (SE) System or Automatic SE System in place of the existing choke system
Manual SE System
The manual SE system is the manual fuel increase systemWhen the choke knob is pulled, the SE valve at the end of the wire is pulled up and the fuel increase circuit opensThe air enters the circuit through the SE air jet this time, producing vacuumThe fuel is drawn and supplied from the float chamber via the SE jet by this vacuum, and it is injected to the main bore to provide the rich aidfuel mixture to the engine