Crankshaft BGM PRO for Vespa GS150 and Motovespa 150 S, Sprint, GS models.
Made from high alloy forged blanks. The crankshaft is designed as a heavy duty tuning crankshaft, and has a 3mm longer stroke (60mm instead of 57mm). This gives the cylinder more displacement, but more important is the fine tuning of the timing angles of intake, exhaust as well as overflow.
Due to the angular function of the connecting rod, not all timing angles grow equally proportionally. While the exhaust changes only slightly, the timing angle of the overflow ports usually increases significantly. Adjusting the exhaust angle (lengthening) is important to get back the original advance exhaust angle (exhaust angle minus overflow angle divided by two). This provides the conditions for a solid performance increase.
Stroke: 60mm (also available as 57mm stroke version)
Connecting rod length: 105mm
Piston pin: Ø15mm
Connecting rod bearing: needle bearing (silver cage top and bottom)
A big advantage of the BGM PRO crankshaft compared to an original one is the use of a high quality connecting rod with needle bearing (instead of a plain bearing bushing) as well as a slotted lower connecting rod eye. The oil requirement is hereby significantly reduced so that the engines can be driven with today`s high quality oils without problems even with 1:50 mixture.
The BGM PRO GS150 crankshaft fits the following vehicles:
Vespa: GS150 (all models: VS1-5T)
Motovespa 150GS (engine 04M), 150S (VTT, V13502C), 150 Sprint (engine 04M)
