Reply To: Umbau von Gt125r motor auf GT250 Motor
If its an EFi 250cc , you need the full donor bike (EFi Tank, All electronics, Exhaust because it has lambda sensors , EFi airbox, EFi dash)
This is assuming you are using an EFi 250.
Otherwise if it is a carb model, upgrade your 125cc jets to 250cc one and keep using the 125 vacuum pump (that electric pump in picture is worthless = too many problems that’s why Hyosung used vacuum pump on all carb models after this)