The carburettors belonging to the DELL'ORTO PHB series are the first choice for mid-range motor tuning projects. They belong to the 'drum carburettors' (with a rounded throttle/choke) and are available with choke diameters between 24 and 30mm. The DELL'ORTO PHB carburettors are the right choice for tuners who wish to extract a little more performance from their scooters motor without having to spend too much of their hard-earned cash!
Regrettably these DELL'ORTO carburettors are not always immediately available. There is however a more economically priced alternative available from YSN. Their carburettors are almost identical in design and function to the DELL'ORTO items and were conceived for similar fields of use. The individual peripheral parts and adjustment components are also mostly identical to those found on DELL'ORTO PHB carburettors, making them interchangeable. Only the centring stud on the throttle slide requires slight modification at some models, when a DELL'ORTO component replaces the original YSN part.
The DELL'ORTO PHB carburettors have a slightly more complex construction than their SI or SHB types, in compensation they allow more possibilities for an individual set up. This can be completed through the use of the wide selection of needles, mixer tubes and jets also available from DELL'ORTO. This fine-tuning, fettling and jet adjustment also requires an individual custom set up by somebody with experience of this work before road use!
These carburettors are equipped as standard with a flip-up choke mechanism, these can of course be replaced by a cable and pull-choke mechanism if desired