19-25 mm, recommended for tuned scooters, as they increase both performance and engine durability. They are mounted on original intake manifolds and original air filters (exception: Peugeot scooters, only racing air filters fit). Main jets may need to be adjusted on some vehicles. - 19 mm = improved acceleration and torque - recommended for stop-and-go operation - 21 mm = significant power increase with substantial RPM increases, primarily in the upper RPM range. Very suitable for top speed. Carburetor PHVA 17.5 (order no. 7.432.728/9) is also suitable for tuning all PHVA 10-12-14 models! Not street legal! Item Type Version Carburetor complete Features Racing carburetor, not street legal Type PHBL