Crankshaft -BGM PRO Racing (rotary valve), 51mm stroke, 97mm conrod- conversion Vespa PK50 XL/XL2 to 125cc (Ø=20mm cone)

• The PK125S still has the small crankshaft type with small, pointed 19mm cone of the Primavera and ET3 models.PK125ETS and PK125XL2 have a larger bearing seat (25mm) on both the shaft and crankcase than all other small frame models. The cone, however, 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 have to use a special conversion bearing with a shaft seal due to the large bearing and shaft seal diameter.

To avoid this effort, we have a crankshaft type that was never built by Vespa itself. A hybrid shaft from the long stroke of the 125cc vehicles in combination with the bearing seat and cone of the PK50XL models.
The here offered shaft fits therefore in all V50, Primavera, ET3 and PK50 engine cases!
So you can use the usual bearings and shaft seals, but still have the stable bearing seat and large cone for conversion to an electronic ignition available.

material:
BGM crankshafts are forged like in the good old Piaggio times. During forging, the material is pressed together under temperature and 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 compared to crankshafts made to order by other manufacturers whose materials used often do not even reach the level of a series shaft.

Tuning:
The high quality of the material used also allows the use of very light-weight spark plugs without the risk of crankshaft damage. This allows a better acceleration behaviour to be combined with a considerably increased durability of the engine. This is particularly important on engines with large displacement and high rpm.

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 crankshaft type.
With our BGM ignition kit, even the otherwise strongly - underexposed - 6V Vespas can enjoy the brilliant halogen light.

Take-off angle:
The take-off angle of this crankshaft is longer compared to a standard 125cc shaft.

For tuning cylinders the standard shaft with its clearly too short intake time does not come along. At a certain rpm level the crankshaft will be shut off.

The engine can be tuned with the optimized control angles of our shaft as if an original Piaggio shaft was used. Nevertheless, the extended intake angle ensures that even completely made engines can turn at full power.

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

• stroke:51mm
• conrod length: 97mm
• control angle: Sport/Racing
• cone type: PK XL50
• Conversion of ignition/pole wheel necessary: Yes
• Bearing seat: 20mm (6204 ball bearing and 20mm shaft seal)

Attention: Shaft DOES NOT fit in PK125ETS or PK125XL2 engine housing!