Flowed Crankshaft SERIE PRO
by Worb5 for Vespa PK50/S/SS
reed valve, stroke 43,0mm, conrod 87,0mm,
cone 20/20mm, M12
The Flowed crankshafts belong to the Low Primary Compression (LPC) crankshaft type which originally leave the factory as MAZZUCHELLI or TAMENI full circle crankshafts. The SERIE PRO range of crankshafts are produced by the German tuners WORB5.
These flowed crankshafts are specially machined to optimise gas flow in the pre-combustion area of the crankcase. The crankwebs have been modified to enable the fuel mixture free flow, unhindered from the turbulence created by the crankshaft. This design also allows a higher volume of fuel mixture to enter the crankcase and so enable a higher compression of gases above the piston in the combustion area. This combination facilitates a wider power band and consequently higher maximum power. Flowed crankshafts are only suitable for use in reed valve motors. The original Vespa disc valve mechanism provided by the clutch side crank web is no longer possible with this heavily altered crankshaft.
Conclusion: Perfect for reed valve motors. Larger, gas flowed ports and inlets are finally possible!
SIP community user „rigger“, England:
“Flowed/mapped for your performance. Gas/oil decreased resistance. Equals more power on demand. Throttle response is even better.”
Flowed crankshaft / stroke 43mm / connecting rod 87mm / 20/20mm, M12
Flowed crankshaft with Ø 82mm crankweb (flywheel side), Ø 87mm crankweb (rotary valve side), 87mm connecting rod, lower connecting rod bearing = sillver bearing, oil seal housing 20mm, bearing housing 20mm, stump cone with M12 thread, incl. piston rod bearing
SIP-TIP: New bearings, oil seals and keys are a must. Same goes for sealing kit, clutch-, and flywheel nuts. You?ll also need a POLINI, MALOSSI or HHP reed valve manifold.
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