Piaggio 4316255 Complete Crankshaft 50 2T – Zip, Typhoon, NRG, Liberty, Vespa and Gilera

The Piaggio 4316255 complete crankshaft is the original replacement part for Piaggio Group 50cc 2-stroke engines, both air-cooled and liquid-cooled. It includes the two crankshaft halves, the crank pin, and the pre-assembled connecting rod, with a 39.3 mm stroke, 80 mm connecting rod center-to-center distance, and 12 mm Ø gudgeon pin. It fits Piaggio Zip, Typhoon, NRG, Liberty, Free, Fly, and Sfera; Vespa ET2, LX, LXV, S, Primavera, and Sprint 50cc 2T; Gilera Stalker, Runner, Storm, DNA, Ice, and Easy Moving; and Aprilia Mojito, Sport City ONE, SR Motard, and Scarabeo 50cc 2T. Product code 4316255.

✓ Strengths

• Original Piaggio spare part – this is the official part number from the Piaggio Group parts catalog, not an aftermarket equivalent.
• Crankshaft complete with connecting rod – arrives pre-assembled and within factory tolerances: there is no need to pair the connecting rod and pin separately.
• Original dimensions – 39.3 mm stroke, 80 mm connecting rod center-to-center distance, 12 mm Ø gudgeon pin: displacement and compression ratio remain standard.
• Connecting rod small end needle cage included – included in the package, as shown in the photo.
• One code for the entire 50cc 2T family – the same crankshaft covers thirty years of Piaggio, Gilera, Aprilia, and Vespa scooters.

Technical specifications

Vehicle compatibility

The list is taken from the official Piaggio parts catalog (B2B area). If you have any doubts, send us your scooter's chassis number and we will verify the correct part number for you.

Who it is perfect for

This is the part you need when a 50cc 2T has knocking, whistling from the bottom end, or a failed connecting rod: for workshops rebuilding engines after a seizure, or enthusiasts restoring a Zip, Typhoon, NRG, or Vespa ET2 with the engine opened up on the workbench. Installing the original crankshaft instead of a refurbished one means starting back with factory specs, with no surprises regarding axial play and balancing.

Frequently Asked Questions

Which scooters does the Piaggio 4316255 crankshaft fit?
It fits Piaggio Group 50cc 2T engines: Piaggio Zip, Typhoon, NRG, Liberty, Free, Fly, Sfera, Diesis, and NTT; Vespa ET2, LX, LXV, S, Primavera, and Sprint 50cc 2T; Gilera Stalker, Runner, Storm, DNA, Ice, and Easy Moving; Aprilia Mojito Custom, Sport City ONE, SR Motard, and Scarabeo 50cc 2T. The table above shows the exact models and years.

What are the dimensions of this crankshaft?
It has a 39.3 mm stroke, 80 mm connecting rod center-to-center distance, and a 12 mm diameter gudgeon pin: these are the original specifications for the Piaggio 50cc 2T. Since these are the standard factory measurements, the displacement, compression ratio, and timing remain as specified by the manufacturer, and the original cylinder can be reassembled without spacers.

What does the package contain?
It contains a complete crankshaft, i.e., the two halves with the crank pin and the pre-assembled connecting rod, plus the small end needle cage, as shown in the photo. Main bearings, oil seals, and crankcase gaskets are not included and must be ordered separately.

When should the crankshaft be replaced?
It should be replaced when the connecting rod has radial or axial play outside of tolerances, after a seizure that has scored the pin, when the engine knocks from the bottom end when hot, or when the main bearings have damaged their housings. In all these cases, refurbishing is not cost-effective: it is better to replace the entire crankshaft assembly.

Is it original Piaggio or an equivalent?
It is the genuine Piaggio 4316255 factory replacement part, as used for original equipment. It is not an aftermarket or refurbished crankshaft: the dimensions, balancing, and steel treatment are exactly as specified by the manufacturer, ensuring it fits into the original crankcases without any modifications.

How can I be sure it is the right one for my scooter?
Check the model and year in the compatibility table: if your scooter is not listed, or if you have a special version, write to us with your chassis number. We will check the part number in the official Piaggio catalog and confirm if this crankshaft is the correct one for your engine.