BFA 150 cc High-End Racing Cylinder for Vespa Smallframe – Ø58 mm, 56.7 mm stroke, direct intake with diaphragm, 3-piece exhaust, and original Piaggio stud configuration.
The BFA 150 cc was developed specifically for the performance-oriented 150-cm³ class of Vespa Smallframe models. With a 58 mm bore, 56.7 mm stroke, five overflow channels, and a direct intake with a diaphragm, it features a cylinder design consistently optimized for high filling efficiency and power.
Of particular interest is the combination of the original Piaggio stud pattern and very wide flow channels. This preserves the classic Smallframe mounting geometry, while at the same time requiring an engine case with ample material and sufficient surface area in the flow channel area.
150 cc Ø58 mm 56.7 mm stroke 5 overflow ports 3-piece exhaust Direct-inlet diaphragm Intake port Ø40 mm
The BFA 150 combines a highly performance-oriented cylinder design with the well-known Smallframe stud-mounted layout. This keeps the basic mounting geometry classic, even though the cylinder utilizes significantly larger channel cross-sections than a production-spec Smallframe cylinder.
The overflow ports, in particular, are very wide. The diameter across the ports at the crankcase sealing surface is approximately 100 mm. Accordingly, a crankcase base with sufficient material and contact area is essential.
A BFA engine case is the obvious choice as a base for this cylinder. The wider crankshaft mounting and the large available area in the area of the overflow ports are very well suited to the cylinder’s extremely wide port geometry.
An original Piaggio Smallframe housing can generally be used, but it requires extensive modifications. Particularly in the area of the transfer ports, a great deal of material must be adapted or added so that the large port areas can be effectively implemented.
The cylinder geometry operates with a 56.7 mm stroke. The data provided specifies a connecting rod length of 115 mm; for BFA engine cases, a combination with a 110 mm connecting rod is specified.
Since the connecting rod length directly affects cylinder position, piston position, and squish edge, the specific combination of engine block, crankshaft, spacers, and cylinders should be measured before final assembly.
The cylinder has five overflow channels. The large channel cross-sectional area is an essential component of the BFA concept and enables high gas flow in a performance-oriented engine design.
The wide span of the overflow channels is also the reason why a standard Piaggio engine block can only be meaningfully adapted with considerable effort.
The intake flows directly into the cylinder via a diaphragm. This makes the fuel-air mixture control independent of a traditional rotary valve in the engine case.
The diaphragm and intake manifold are included in the scope of delivery. The intake manifold has a diameter of 40 mm and is therefore designed for high-performance carburetor setups.
The BFA 150 features a three-part exhaust. In addition to the central main exhaust port, additional exhaust ports are used. This allows for a large effective exhaust area to be achieved without having to make the central exhaust port excessively wide.
The cylinder is made of aluminum. The piston features a single piston ring and a 15-mm-diameter piston pin. The single-ring design reduces the friction surface and is typical of performance-oriented cylinder designs.
The spark plug is located centrally in the cylinder head. An NGK B9ES spark plug is recommended.
| Recommended spark plug | NGK B9ES |
|---|---|
| Recommended ignition timing | 17° before TDC |
| Manufacturer | BFA |
|---|---|
| Displacement class | 150 cc |
| Engine Housing | Recommended by BFA |
| Material | Aluminum |
| Bore | Ø58 mm |
| Stroke | 56.7 mm |
| Connecting rod length | 115 mm; 110 mm for BFA engine blocks |
| Piston rings | 1 |
| Piston pin | Ø15 mm |
| Overflow valve | 5 |
| Diameter across channels at housing sealing surface | approx. 100 mm |
| Inlet | Direct inlet with diaphragm |
| Suction port | Ø40 mm |
| Outlet | 3-piece |
| Cylinder head | Included |
| Spark plug position | Center |
| Recommended spark plug | NGK B9ES |
| Recommended ignition timing | 17° before TDC |
| Exhaust connection | 3-hole mounting |
The BFA 150 is a performance-oriented tuning and racing cylinder. The cylinder kit does not include general approval for use on public roads; applicable regulations and any necessary individual approval must be verified prior to use.
The BFA 150 is a small-frame cylinder developed without compromise for the high-performance 150-cm³ class. Five large-diameter overflow ports, a direct intake with a diaphragm, a 3-piece exhaust, and a Ø40-mm intake manifold form a foundation consistently designed for high gas flow.
The original stud pattern is retained, while the extremely wide port geometry requires an engine case with ample material and sufficient surface area. A compatible BFA engine case is therefore the ideal foundation; a stock Piaggio case requires extensive modifications.
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