• The PK125S still has the small crankshaft type with a small, pointed 19mm cone on the Primavera and ET3 models.
• The PK125ETS and PK125XL2 have a larger bearing seat (25mm) on both the shaft and in the crankhouse than all other small-frame models. The cone, on the other hand, is identical to that of the PK50XL/ XL2 models. So if you want to install such a 125cc ETS shaft in a V50 or PK50, you are forced to use a special conversion bearing including a shaft seal ring due to the large bearing and shaft seal diameter.

So that this effort is not necessary, we have a type of crankshaft that was never built in this way by Vespa itself. A hybrid shaft made from the long stroke of 125cc vehicles in combination with the bearing seat and cone of the PK50XL models.
The shaft offered here therefore fits all V50, Primavera, ET3 and PK50 motor housings!
This allows you to use the usual bearings and shaft seals, but still has the sturdy bearing seat and large cone available for conversion to electronic ignition.

Material:
The BGM crankshafts are forged just like in the good old Piaggio days. During forging, the material is pressed together under temperature and at high pressure. This results in a higher density of the material. Heat is dissipated much better. The material is more resistant to distortion. This is a huge advantage over the custom-made crankshafts from other manufacturers whose materials often do not even reach the level of a standard shaft.

Tuning:
The high quality of the material used also allows the use of very lightweight pole wheels without the risk of crankshaft damage. As a result, better acceleration behavior can be combined with significantly increased engine durability. This is particularly important on high-displacement and high-speed engines.

Improvements:
An interesting side effect is the conversion to an electronic 12V ignition, which is always necessary when converting a Vespa 50 or Primavera 125 to this type of crankshaft.
With our BGM ignition kit, even the otherwise heavily -underexposed- 6V Vespen can enjoy bright halogen light.

Control angle:
The control angles of this crankshaft are extended compared to a standard 125cc shaft.

With tuning cylinders, the standard shaft, with its significantly too short intake time, does not keep up. When a certain speed level is reached, it is then literally sealed off.

With the optimised control angles of our shaft, the motor can be adjusted as if an original Piaggio shaft were installed. Nevertheless, the extended intake angle ensures that self-made engines can fully turn off.

In addition, the rotary vane inlet of the housing can be extended to create sufficient space for larger carburettors and to further increase the engine's performance readiness.

• Stroke: 51mm
• Conrod length: 97mm
• Control angle: Sport/Racing
• Cone type: PK XL50
• Ignition/flywheel conversion required: Yes
• Bearing seat: 20mm (6204 ball bearing and 20mm shaft sealing ring)

Attention: Shaft NOT suitable for PK125ETS or PK125XL2 motor housings!

About the manufacturer BGM

BGM is a leading brand for high-quality spare parts and accessories for scooters, motorcycles and classic Vespa models that stands for quality, precision and innovation. With an uncompromising “Made in Germany” philosophy, BGM develops durable products in collaboration with leading engineers and under strict quality controls. Whether restoring vintage cars or tuning modern scooters — BGM is the first choice for discerning drivers. Thanks to first-class workmanship and a wide range of products, BGM offers ideal solutions for performance, everyday use and individuality.