This CNC machined crankcase represents an ideal basis for the extreme performance possible when these BSG parts are properly combined. A full-circle crankshaft, especially developed for this motor, is its heart.
These BSG full-circle crankshafts are extremely solidly constructed. They are manufactured in a small engineering workshop which primarily produces parts for use in Moto GP race bikes, guaranteeing a high end quality. The bearing collars on both sides of the crankshaft have a diameter of 25mm and 20mm for the oil seal collar. The shaft stump, upon which the primary drive is located, has a diameter of 17mm making it 3mm thicker than other similar crankshafts. This peculiarity makes the use of the BSG gear cogs essential. A primary drive holding nut and woodruff key are also included with this kit. Both crank-webs measure a mighty 90.6mm in diameter and are each 20.2mm thick. These full-circle webs are also provided with heavy metal balancing weights to enable them to be very finely balanced, guaranteeing a smoothly running motor throughout the whole rev-range. The con-rod, originally a Moto GP component from APRILIA, is especially stable during use due to its reinforced design. The most widely used version has a length of 115mm with 110 and 105mm lengths also being available from stock. The longer con-rods facilitate a higher primary compression, denser fuel charge and improved performance in the complete rev-range. This crankshaft is available with either a 54.4 or 56mm stroke, with the 56mm version being the more popular size used. When combined with a 60mm bore cylinder the cubic capacity reaches a whopping 158cc! This BSG crankshaft is only compatible with the crankcase also produced by BSG and cannot be used in standard specification motors. This is the most extreme crankshaft that we have ever encountered for the Vespa Smallframe motor! Who dares wins!
Conclusion: Little wonder that, in combination with a BSG crankcase and a suitable performance cylinder kit, over 40PS can be achieved!
Full-circle HPC crankshaft / 54.4-56mm stroke / 105,110 & 115mm con-rod lengths / 20, 25mm / M 12
Full-circle crankshaft with 90.2mm diameter crank-webs, fine balanced, 105/110 & 115mm Moto GP con-rod lengths, oil-seal collar : 20mm, bearing collar diameters : 25mm, large crankshaft stub with a M 12 thread, a small-end bearing / woodruff keys & M 12 nut are included.
SIP-TIP : Do not forget to order suitable oil-seals and bearings. The BSG produced crankcase and primary drive cogs are essential!