Piston Piaggio Original – 125cc LEM / IGET AC 3V – Vespa Primavera, Sprint, LX, S, 946, Piaggio Liberty, Fly – Category A, B, C, D
Original Piaggio pistons for air-cooled 125cc four-stroke engines of the LEM and IGET series with three valves. These pistons are designed to replace worn or damaged standard pistons and are available in four different size categories. They allow targeted repair of the piston and cylinder assembly while taking into account the manufacturing tolerances specified by the manufacturer.
The pistons are offered in categories A, B, C and D, also designated as categories 1, 2, 3 and 4. The different versions are distinguished by their dimensional classification, allowing the selection of a piston matched to the existing cylinder bore.
Piaggio LEM – the technical foundation of the 125cc three-valve engines
LEM stands for Low Emission Motor at Piaggio. The designation describes an engine generation developed with the aim of reducing fuel consumption and exhaust emissions while improving everyday usability and smooth engine operation.
The LEM engines were introduced in the early 2010s and were used in models including the Vespa LX, Vespa S, Vespa Primavera and Vespa Sprint, as well as various Piaggio models.
A key design feature of this engine generation is the three-valve cylinder head. Two intake valves supply the fresh air-fuel charge, while one exhaust valve allows the combustion gases to escape. The valves are operated by an overhead, chain-driven camshaft.
The three-valve configuration combines a compact design with controlled gas exchange. Compared with basic two-valve designs, the use of two intake valves provides additional possibilities for optimising the intake flow area and airflow characteristics within the cylinder head.
The engines are designed as air-cooled, single-cylinder four-stroke units. Heat generated during combustion is transferred from the cooling surfaces of the cylinder and cylinder head to an airflow produced by a cooling fan.
With a cylinder bore of 52mm and a piston stroke of 58.6mm, the engine has an actual displacement of approximately 124cc. The designation 125cc refers to the conventional engine capacity class.
Electronic fuel injection is used for mixture preparation. It enables fuel delivery to be adjusted according to the relevant operating conditions.
From LEM to IGET – the evolution of Piaggio engine technology
IGET stands for Italian Green Experience Technology. Piaggio uses this name for a further-developed generation of its four-stroke engines, with particular attention paid to combustion efficiency, mechanical friction losses and compliance with modern emissions regulations.
IGET engines build on technical concepts established in earlier Piaggio four-stroke engines. These include the compact single-cylinder configuration, electronic fuel injection and an engine design intended for economical everyday operation.
In the air-cooled 125cc three-valve engines, the basic configuration with two intake valves, one exhaust valve and an overhead camshaft is retained. Further development includes adjustments to the combustion process and various individual design features of the engine.
Although LEM and IGET versions share a similar basic design, they may use different component versions. The specific engine variant must therefore be considered when ordering replacement parts. Correct identification is based on the original Piaggio part number and the appropriate piston size category.
Four piston categories for precise dimensional matching
During the series production of pistons and cylinders, small dimensional variations occur within the permitted manufacturing tolerances. Piaggio uses several size categories to compensate for these differences.
Four categories are available for the original pistons described here. The corresponding Piaggio original part numbers are:
- Category A / 1 – Piaggio original part number B0180110001
- Category B / 2 – Piaggio original part number B0180110002
- Category C / 3 – Piaggio original part number B0180110003
- Category D / 4 – Piaggio original part number B0180110004
The size categories are used to match the piston to the existing cylinder bore. The decisive factor is the piston-to-cylinder clearance specified by the manufacturer.
Categories A to D are not conventional oversize repair pistons. These gradations fall within the standard manufacturing dimensions and are not intended for use in cylinders that have been rebored to a significantly larger diameter.
The correct category must be determined from the existing cylinder markings and the actual cylinder dimensions. The vehicle model or year of manufacture alone is not sufficient for reliable selection.
Piston crown and construction details
The piston features a distinctly recessed, bowl-shaped crown. This contour forms part of the piston geometry matched to the combustion chamber and influences, among other things, the compression ratio specified by the engine design.
The product images clearly show the precisely machined surface of the piston crown and the concentric machining marks. Additional recesses are located around the outer area and form part of the crown's design.
The circumferential piston ring grooves are positioned below the piston crown. The pistons shown in the images are fitted with piston rings, which perform different functions within the engine.
The compression rings seal the combustion chamber and assist heat transfer from the piston to the cylinder wall. The oil control ring regulates the lubricating oil film on the cylinder bore and returns excess oil.
The piston skirt features machined sliding surfaces that guide the piston as it moves within the cylinder bore. The piston pin bosses positioned on either side provide the connection to the connecting rod.
The product images also show two separate piston pin retaining clips. These secure the piston pin axially and prevent sideways movement during engine operation.
A marking on the piston crown helps ensure correct orientation during installation. The installation direction specified by the manufacturer must be observed.
Technical specifications
- Manufacturer: Piaggio
- Product: original piston for four-stroke engines
- Engine family: LEM / IGET
- Engine version: 125cc AC 3V
- Actual engine displacement: approx. 124cc
- Engine configuration: single-cylinder four-stroke engine
- Number of valves: three
- Valve arrangement: two intake valves, one exhaust valve
- Valve actuation: overhead, chain-driven camshaft
- Cooling: air cooling (AC)
- Fuel system: electronic fuel injection
- Nominal engine bore: 52mm
- Engine stroke: 58.6mm
- Available size categories: A, B, C, D or 1, 2, 3, 4
- Piaggio original part number category A / 1: B0180110001
- Piaggio original part number category B / 2: B0180110002
- Piaggio original part number category C / 3: B0180110003
- Piaggio original part number category D / 4: B0180110004
- Piston crown: recessed, machined contour
- Piston rings: shown fitted in the product images
- Piston pin retention: two retaining clips shown in the product images
- Application: replacement due to wear, damage or engine overhaul
Suitable for Vespa
- Vespa 946 125 (2013–)
- Vespa LX 125 (2012–2013)
- Vespa Primavera 125 (2013–)
- Vespa S 125 (2012)
- Vespa Sprint 125 (2014–)
Suitable for Piaggio models
- Piaggio Fly 125 (2012–2015)
- Piaggio Liberty 125 (2017–2024)
Vehicle compatibility applies to the corresponding models equipped with an air-cooled 125cc three-valve engine. As different engine generations and technical versions have been used within certain model ranges, the engine version and required piston size category must be checked before ordering.
Important information on selection and installation
Before replacing the piston, the condition of the cylinder bore must be inspected. In addition to visible damage such as scoring or wear marks, particular attention should be paid to wear, ovality and possible dimensional deviations.
The selection of the correct piston category depends on the dimensional classification and the actual condition of the cylinder. During an engine overhaul, the cylinder bore should be checked using suitable measuring instruments.
Insufficient piston-to-cylinder clearance can result in increased friction and thermal problems. Excessive clearance, on the other hand, can adversely affect piston guidance, sealing and engine noise.
During installation, the specified piston orientation, correct arrangement of the piston rings and piston ring end gap must be observed. The piston pin retaining clips must be fully and correctly seated in their grooves.
The condition of the piston pin, connecting rod small end and associated bearing surfaces should also be checked. Worn or damaged components must be replaced correctly before reassembly.
The four size categories allow precise selection within the standard manufacturing tolerances. However, they do not replace necessary cylinder repairs in cases of excessive wear or damage.
Original Piaggio replacement part for LEM and IGET engines
The original Piaggio pistons with part numbers B0180110001 to B0180110004 are intended for targeted repair of air-cooled 125cc three-valve engines.
Thanks to the four size categories, the piston version matching the existing cylinder can be selected. The correct combination of piston, cylinder and piston rings forms the basis for reliable sealing and the intended mechanical operation of the engine.
An original replacement part for professional repair of 125cc LEM and IGET engines in Vespa Primavera, Sprint, LX, S, 946 and Piaggio Liberty and Fly models.
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