Carburetor -YSN PHBH 28 BS- AW=34mm - with vacuum/oil connection - folding choke

YSN PHBH 28 BS carburetor with AW 34 mm

The YSN PHBH 28 carburetor corresponds to the original in almost every detail. With YSN, we have a very good and reliable manufacturer at our side who continues to produce the legendary carburetors for us. The quality is absolutely comparable with the Italian original and the parts are 99% interchangeable. Only the throttle slides are guided in the carburetor by a slightly longer centering pin. If Dell'Orto throttle slides are to be used, this pin in the cast aluminum can simply be retracted slightly.

A major advantage of the PHB carburetors is their simple and good tunability as well as 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 carburettor usually runs surprisingly well even when tuned too lean, which can unfortunately quickly result in a sticky mixture.

The following basic jetting for the PHBH series has proven to be a good starting point on most scooter engines:

• Mixing tube: AV264
• Needle: X2 or X3
• Secondary jet: 55
• Main jet: 120-145
• Slider: 30 (rich) or 40 (lean)

If problems with the fuel supply are suspected, it is advisable to convert to a larger float needle valve (#250).

BS carburetor = adjusting screws in left suction direction