The fuel tank capacity of Haojue 125-8 series motorcycles is 8.5 liters, including the spare fuel tank of 1.5 liters. Don't fill the tank too full, especially the third car. Too full fuel may damage the carbon canister or fuel evaporation prevention system, and may lead to poor refueling of the car.
The following is taken from the instruction manual of Haojue 125-8.