Piaggio 478547 V-Belt Variator 736x18 – Vespa ET4 125 and Sfera 125

The Piaggio 478547 V-belt is the variator belt that transmits power from the drive pulley to the driven pulley on first-series Vespa ET4 125, Piaggio Sfera 125, and Sfera RST 125 scooters. This is an original Piaggio spare part, measuring 736 x 18 mm, and occupies position 2 on the official "Drive half-pulley" diagram in the spare parts catalog. Product code 478547.

✓ Strengths

• Original catalog size – 736 mm length and 18 mm width: this is the geometry the variator is designed for, which determines acceleration and pickup.
• Original spare part, not an aftermarket equivalent – this is the code prescribed by Piaggio in the catalog for these models.
• Toothed V-belt profile – the inner teeth allow it to be flexible around the tight radii of the variator and limit overheating.
• Maintenance part – this is a wear item: replacing it in time avoids damaging pulleys and rollers, which are much more expensive to replace.
• Stock still available – for vehicles that have been out of production for years, finding the original belt in the correct size is the difficult part.

Technical specifications

Vehicle compatibility

List taken from the official Piaggio spare parts catalog (B2B).

Spare parts from the same diagram

If you open the casing to change the belt, these are the other codes from the official "Drive half-pulley" diagram. Contact us to check availability.

• 82523R – fixed drive half-pulley (position 3)
• 435027 – toothed bushing (position 5)
• 436698 – cup spring (position 6) and 436789 – hex nut (position 7)
• 434409 / 434410 – washers (positions 1 and 4)

Who it is perfect for

This is the right spare part for those keeping a first-series Vespa ET4 125 or a Sfera 125 on the road and want to restore the transmission with the original part, rather than a generic equivalent. If the scooter has become slow on pickup, "slips" on hills, or is making noise from the transmission area, the belt is the first thing to check — and it is also the cheapest thing to replace before wear affects the pulleys and rollers.

Frequently asked questions

Is this belt suitable for my Vespa ET4 125?
It is suitable for the Vespa ET4 125 found in historical catalogs, i.e., the first series with the older engine, and it is the same belt as the Sfera 125 and Sfera RST 125. On later ET4 models, Piaggio changed the engine and belt: in case of doubt, send us your chassis number and we will verify it for you.

How do I know if the belt needs to be changed?
Signs include loss of thrust when starting, slippage on inclines, noise or whistling from the transmission area, and a lower top speed than usual. With the casing open, you should check for cracks in the teeth, frayed edges, and loss of width. The exact replacement interval is in your vehicle's owner's manual.

What is the difference compared to the 841213 belt?
The 841213 is the belt for the more recent 125 and 150 4-stroke Piaggio Group models (Vespa LX, Liberty, Fly, X8, Runner, Atlantic). The 478547 is shorter and fits historical models: Sfera 125 and first-series ET4 125. They are not interchangeable.

Is this an original spare part or an equivalent?
It is an original Piaggio spare part with manufacturer code 478547, the same one that appears on the official exploded diagram of the drive half-pulley. It is not a universal third-party belt.