The YSN PHBH 28 carburetor is almost identical to the original in every detail. With the YSN manufacturer, we have a very good and reliable manufacturer on our side who continues to produce the legendary carburetors for us. The quality is absolutely comparable to the Italian original, and even the parts are 99% interchangeable. Only the throttle slides are guided by a slightly longer centering pin in the carburetor. If Dell'Orto gas sliders are to be used, this pin in the aluminum casting can simply be taken back a little.
A great advantage of PHB carburetors is their easy and good tuning and their insensitivity to weather changes. The PHBH shows quite quickly and clearly whether the mixture is too rich or too lean. A Mikuni or Keihin carburetor usually works surprisingly well, even if tuned too lean, which unfortunately can quickly lead to a problem.

On most scooter engines, the following basic fuel mixture has proven to be a good starting point for the PHBH series

:
Mixing tube: AV264
Needle: X2 or X3
Side nozzle: 55
Main nozzle: 120-145
Slip: 30 (fat) or 40 (lean)
If fuel supply problems are suspected, convert to a larger float needle valve (#250).

BS carburetor = adjustment screws in left intake direction