Crankshaft -BGM Pro Touring (rotary valve) 57mm stroke- Vespa PX200 51906

MATERIAL
The bgm PRO Touring crankshafts are forged. The material is denser and therefore conducts heat better and is more resistant to distortion. In addition to the crank webs, the connecting rod is also forged.

BEARING

The lower connecting rod bearing is lubricated via two large lubrication slots and a total of four additional pockets on the side. The SSC race bearing and side thrust washers provide solid bearing support. The upper connecting rod bearing is lubricated via two lubrication holes. The INA piston pin bearing is included with the crankshaft.

HUB
The shaft is available with 60mm (long stroke) and with 57mm (standard) stroke. With the long-stroke variant, more displacement is achieved, and at the same time the cylinder`s intake angles (overflow and exhaust ports) can be changed to increase performance.

INLET ANGLE

Compared to many other racing shafts, the bgm PRO Touring shaft has a much better inlet timing layout. 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 engine case about 65° after top dead center (depending on the engine case, this varies from the factory). The engine can be tuned well with these timing angles. TIP: If the intake is machined so that the crankshaft clears the intake slot earlier, additional power can be gained. A good value has been found to be approx. 120° from TDC.

RELEASE
The crankshaft design of the PX engines is based on that of the first 125cm³ engines from 1960 with approx. 5 HP power. Unfortunately Piaggio never really changed this design in the later displacement extensions . Thus, the load capacity of the crankshaft with the standard 200cc models with 12HP is mathematically already exhausted. The crank webs are very narrow and have very little overlap (web material that, seen in diameter, is available above the lower crankpin). This means that neither a particularly high interference fit nor a large crankpin can be used, as would be necessary (for the performance of today`s engines).
The BGM PRO Touring crankshafts have a very high material quality and bearing. In addition, the crankpins are glued for maximum torsion resistance. Due to the positive experiences, collected in many thousands of test kilometers of our own daily used engines, we release the BGM PRO Touring crankshafts for engine power up to 25HP. We recommend for engines in this power range the use of a lightened pole wheel with max. 2300gr.

CONCLUSION

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

TIP

It is best to directly order the oil seal 24x35x7 from the Gilera Runner. The Wedi seat of the bgm shaft is wider than usual and can therefore be driven with a double-lipped Viton Wedi. _{AI-translation}