The DELL'ORTO 5mm jet is installed as the main jet on the SHB/PHBD/PHBG. With the PHBL/VHST carburettors they function as idle jets. As the main jet, it is responsible for making a certain amount of petrol available for premixing. As an idle jet, on the PHBL/VHST carburettors, it primarily affects the lower and middle rev range. With all tuning measures, no matter how small, it is necessary for the size of the main jet to be raised, as they mainly impact on the middle and upper rev range.