Honda EM50is Manuel De L'utilisateur page 18

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.
NOTE:
• 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 in the range
on the Engine speed (with eco throttle off) in the ''SPECIFICATION''
page.
ECO THROTTLE SWITCH
OFF
16
(FT, GT, ITT types)
OFF
ON
(UT, RT types)
ON