Vespa PX125, PX150 Crankshaft -BGM Pro Touring (rotary valve) 57mm stroke, 105mm conrod




The bgm PRO Touring crankshafts are forged. The material is more dense, thus dissipating heat better and is therefore more resistant to distortion. Besides the crank webs, the connecting rod is also forged and then CNC machined.

The lower conrod bearing is lubricated via two large lubrication slots and a total of four additional pockets on the side. The SSC race bearing and the lateral thrust washers ensure a solid bearing. Lubrication of the upper conrod bearing is done via two lubrication holes. The INA piston pin bearing is included with the crankshaft.

The shaft is available with 60mm (long stroke) and with 57mm (standard) stroke. With the long stroke version more displacement is achieved, at the same time the control angles of the cylinder (overflow and exhaust ports) can be changed to increase performance.

Compared to many other racing shafts the bgm PRO Touring Shaft has a much better layout of the intake time. For tuning cylinders the standard shaft with its very short intake time cannot keep up. The bgm PRO shaft, on the other hand, closes on a PX motor housing approx. 58° after top dead center (depending on the motor housing, this varies ex works). The motor can be well tuned with these control angles. TIP: If the intake is machined in a way that the crankshaft opens the intake slot earlier, additional power can be gained. A good value is about 120° TDC.

The crankshaft design of the PX engines is based on that of the first 125cm³ engines from 1960 with about 5 HP power. Unfortunately Piaggio never really changed this design during the later extensions. So the load capacity of the crankshaft with the standard 200ccm models with 12 hp is mathematically already exhausted. The crank webs are very narrow and have very little overlap (web material which, seen in diameter, is available above the lower crankpin). This means that neither a particularly high pressing dimension nor a large crankpin can be used, as would be necessary (for the performance of today’s engines).
The BGM crankshafts are approved for a performance of up to approx. 20 HP due to their high material quality and bearings. For engines in this power range we recommend the use of a lightened pole wheel with max. 2300gr.

The bottom line is that the bgm PRO crankshaft offers highest quality in all aspects for every component. Precision in production, materials used and above all the precise balancing leave nothing to be desired. This guarantees extremely quiet and vibration-free engine running.

It is best to order the shaft seal 24x35x7 from Gilera Runner directly with the crankshaft. The wedi seat of the bgm shaft is wider than usual and can therefore be used with a double lip Viton Wedi.