BFA/FRT 288 Solid-Flange Crankshaft – High-End Crankshaft Assembly for Vespa Smallframe
60 mm stroke, 120 mm race connecting rods, and a solid crankshaft construction weighing approximately 2.7 kg. The BFA/FRT full-flange crankshaft was developed specifically for the high-displacement BFA-288 engine concept. Its exceptionally robust construction, meticulous balancing, and toothed primary sprocket mount are consistently designed for high power and enormous torque.
This is not a standard small-frame crankshaft that has simply been reinforced. BFA has redesigned the entire crankshaft assembly for its specialized engine block—featuring wide solid-flange design, high-quality race connecting rods, and a power transmission system that meets the demands of large-displacement race engines.
Key Features at a Glance
- Solid, full-web crankshaft: High rigidity and load-bearing capacity for high-performance engines
- Elaborate fine balancing: 16 weight inserts, 8 of which are made of high-density tungsten
- High flywheel mass: Approximately 2.7 kg crankshaft weight for smoother rotational motion
- 120-mm race connecting rods: High-quality, polished connecting rod design
- Toothed primary sprocket mount: Form-fit power transmission without the traditional small keyway connection
- BFA system component: Tailored to the special engine case and the BFA-288 direct-diaphragm cylinder
16 balancing weights—8 of which are made of tungsten
A distinctive feature of this crankshaft is its sophisticated balancing with a total of 16 weight inserts, including 8 made of tungsten.
Tungsten has a significantly higher density than steel. This allows the mass distribution of the crankshaft to be specifically controlled without having to make the webs unnecessarily large. This is a particularly important design advantage for a solid, full-web crankshaft with a long stroke and a heavy piston.
Combined with its high curb weight of approximately 2.7 kg, the crankshaft provides a substantial rotating mass. This can reduce speed fluctuations between individual power strokes and contributes to smooth engine operation.
The fine balancing is tailored to the BFA engine concept. The actual vibration behavior also depends on piston weight, engine mounting, and operating speed.
120-mm race connecting rod and 60-mm stroke
The high-quality race connecting rod has a center-to-center distance of 120 mm and is designed to withstand the high mechanical stresses of the BFA engine. The polished surface is part of the meticulous craftsmanship of the crankshaft assembly.
With a 60-mm stroke, the crankshaft, together with the 78-mm cylinder, forms the basis of the BFA-288 engine design.
The connecting rod is designed for a 18 mm diameter piston pin. The corresponding piston pin needle bearing measures 18 × 22 × 22 mm.
Toothed Mounting for the Primary Drive
The connection to the primary pinion is another highlight of this crankshaft. BFA uses a toothed, form-fit pinion housing instead of a conventional small-frame connection with a small key.
This allows torque to be transmitted across multiple load-bearing tooth flanks. Especially with very high-performance engines, this design is a sensible solution for reliably transferring high loads to the primary drive.
Important: The gear teeth require a specially matched BFA primary pinion. Conventional Piaggio Smallframe primary pinions are not compatible.
Technical Specifications
| Feature |
Design |
| Manufacturer | BFA/FRT, Italy |
| Crankshaft Type | Solid-flange crankshaft |
| Engine design | BFA 288 Smallframe |
| Stroke | 60 mm |
| Connecting rod length | 120 mm |
| Connecting Rod Design | Race, polished |
| Piston pin diameter | Ø18 mm |
| Piston pin bearing | 18 × 22 × 22 mm |
| Balancing | Precision-balanced |
| Balancing inserts | 16, 8 of which are made of tungsten |
| Crankshaft weight | Approx. 2.7 kg |
| Primary pinion housing | Toothed |
| Intake design | Direct diaphragm on the cylinder |
| Engine housing | Special BFA small-frame housing |
| Applications | High-end tuning / motorsports |
Installation and compatible components
The BFA crankshaft is part of a proprietary engine system. Assembly requires the appropriate BFA engine block, the cylinder matched to it, and the associated drive components.
The following points should be observed during assembly:
- Engine block: Use only the BFA block intended for this crankshaft.
- Primary drive: Include the appropriate pinion with a toothed mounting.
- Piston pin: Use a Ø18 mm pin and the appropriate needle bearing (18 × 22 × 22 mm).
- Bearings: Select crankshaft bearings and shaft seals according to the BFA housing specifications.
- Assembly inspection: Check for concentricity, axial alignment, free movement, and proper fit of the primary components.
- Cylinder position: Check the compression edge and valve timing after assembly.
The BFA crankshaft is not intended as a direct replacement for an original Piaggio Smallframe crankshaft.
Compatible Vehicles
For installing a BFA-288 engine in compatible Vespa Smallframe frames, for example:
- Vespa V50 / 50 Special
- Vespa 90 / 100
- Vespa 125 Primavera / PV125
- Vespa 125 Primavera ET3
- Vespa PK 50 / 80 / 125
- Vespa PK S / XL / XL2
Note: Vehicle compatibility always requires the corresponding BFA special engine housing. The crankshaft does not fit directly into standard Piaggio engine housings.
Scope of Delivery
- 1 × BFA/FRT solid-flange crankshaft, 60 mm stroke / 120 mm connecting rod
Additional parts such as crankshaft bearings, shaft seals, and the toothed primary pinion are not included with the crankshaft described here and must be selected to match the engine configuration.
Frequently Asked Questions (FAQ)
Does the crankshaft fit into an original Vespa small-frame crankcase?
No. The particularly wide and solid design was developed for the special BFA engine case. Direct installation in a standard Piaggio case is not intended.
Why does BFA use tungsten weights?
Tungsten has a particularly high density. This allows the mass distribution of the crank arms to be precisely adjusted and the crankshaft to be optimized for the piston and connecting rod masses of the BFA engine.
What is the advantage of the toothed primary sprocket mount?
The gear teeth transmit torque via a positive-lock engagement across multiple tooth flanks. This is advantageous under the high loads of a high-performance engine. A correspondingly compatible BFA primary pinion is required.
Is the crankshaft suitable for rotary vane engines?
No. The solid-flange crankshaft is designed for the BFA engine concept with a diaphragm-controlled direct intake at the cylinder. It does not have a control flange for a classic Piaggio rotary valve intake.
Which piston pin bearing is required?
The crankshaft is designed for a piston pin with a diameter of 18 mm. The corresponding needle bearing has dimensions of 18 × 22 × 22 mm.
Is the crankshaft approved for use on public roads?
The crankshaft is intended for motorsports and racing engines. There is no general road approval for the high-performance engine built with it.
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