Honda EU65is Manuel De L'utilisateur page 17

Eco Throttle
ON:
Engine speed is kept at idle automatically when the electrical
appliance is disconnected and it returns to the proper speed by the
electrical load when electrical appliance is connected. This position is
recommended to minimize the fuel consumption while in operation.
When high electrical load appliances is connected simultaneously,
turn the Eco Throttle switch to the OFF position to reduce voltage
changes.
Eco Throttle system does not operate sufficiently if the electrical
appliance requires the momentary electric power.
OFF:
Eco Throttle system does not operate. Engine speed is kept over rated
speed.
O O F F F F
14
ECO THROTTLE SWITCH
O O N N