Crankcase SIP BFA 306

A set of strengthened engine casings for Vespa Largeframe models. They provide a solid basis with potential for solidly road-tuned everyday motors through to high-tech racing machines.

The spine of any engine, especially with Vespas, is provided by its casings. Although they only have a secondary function as far as providing power is concerned, no motor can be stronger than the construction of its casings allows. The load carrying capacity of engine casings decides the amount of power that can be safely transmitted through the gearbox to the rear wheel and ultimately, the road. The dimensions of the engine casings determines the size of the peripheral components that can be effectively included in the set up and with it the power they can together provide. The construction of the crankcase and the cylinder base gasket surface area are an indication of the limits of the potential performance envelope.

• Plenty of space for modern, powerful tuning components.
• A massive, stable and elaborately balanced crankshaft
• Very sturdy case, manufactured with extremely tight tolerances

The SIP-BFA engine casings redefine the boundaries of tuning Largeframe Vespas. Firstly, they are provided with an impressive framework upon which muscled components can flex their power and a plug and play capacity of a whopping 306cc is enabled! The potential power output has now been raised beyond the 60PS mark. The gearbox, clutch and crankshaft are now held sturdily and exactly in position.

In spite of its improved overall dimensioning the basic, essential form of these engine casings is identical to that of the PIAGGIO originals, including identical distancing between the gearbox shafts. All of the gearbox components are compatible with engine projects based on the original engine casings. The area surrounding the original basic form has been expanded due to the design of these BFA produced engine casings. There is now adequate elbow room for their larger crankshaft, more capable of withstanding the increased performance, while also providing an even more smoother running motor due to its larger mass of 3.5Kg.

The right space for every cylinder

There is also increased room for the positioning of cylinders, facilitating simpler integration of any established Vespa tuning cylinder kits. They provide an excellent basis for a much tougher engine and swing-arm set up with, for example, the fitting of a MALOSSI 221cc cylinder. Another advantage of this increase in area is the potential for countless possibilities to enlarge the cubic capacity and assimilate many exotic types of cylinder, with even higher possible levels of power output. Even unusual and extravagant transfer port layouts can be catered for! The ultimate plug and play solution is represented by the BFA 306cc cylinder with its almost inexhaustible reserves of potential performance. These engine casings and components were designed to complement it ideally and due to its compatibility with the air-cooling feature of Vespas, very simply further modified and/or tuned.

An especially advantageous aspect of the construction of these engines is the massive design of the output shafts mountings. The 70mm wide inlet port is located directly beneath the base of the cylinder and is spread sideways over both crankcase halves. The original 24mm SI carburettor can no longer be used but the Dell'Orto PHS carburettors, available with a diameter of between 28 and 39.5mm, exploit the space provided ideally. They are also more capable of providing a more reliable supply of fuel than the original items. The fuel supply to the carburettor itself can be additionally secured through the use of the fuel-pump vacuum supply connection, already integrated as standard into the design of the crankcases. The two crankshaft bearings have an identical outer diameter of 62mm and they also share the same width of 16mm. The clutch-side of the crankshaft has an outer race bearing fitted, the flywheel-side is taken care of by a fixed version.

We have these SIP-BFA engine casings available in six separate versions:

• 306 (#78245500) The casings are prepared for the inclusion of the 306cc BFA cylinder, along with its 64mm BFA crankshaft. Distance between BFA cylinder mounting studs: 100mm x 100mm
• 225 (#78242250) These casings possess the same cylinder stud spacing as the Vespa PX 125-150 models. The cylinder opening and transfer ports match the requirements of the 225cc BFA cylinder. For BFA crankshaft 60mm stroke.
• MALOSSI 221 (#78242100) The casings are prepared to be suitable with the MALOSSI 221cc cylinder, including its matching transfer ports. Cylinder stud spacing as the Vespa PX 200 models. For BFA crankshaft 60mm stroke.
• MALOSSI 187 (#78242300) The casings are prepared to be suitable with the MALOSSI 187cc cylinder, including its matching transfer port layout. Cylinder stud spacing as the Vespa PX 125-150 models. For BFA crankshaft 60mm stroke.
• 200 (#78242500) This version is intended as a direct replacement for the original Vespa Largeframe PX 200 engine casings. Identical with the #78242100, apart from the over-dimensioned transfer ports.
• 125-150 (#78242400) This version is intended as a direct replacement for the original Vespa Largeframe PX 125-150 engine casings. Identical with the #78242300, apart from the over-dimensioned transfer ports.

Please note: The SIP–BFA engine casings provide an excellent basis to realize every intended or even imaginable Largeframe Vespa engine tuning project, the sky is the limit! Due to its extensively modified and improved design, experience of and skill in such projects will be necessary for a completely reliable and correct engine-build. We strongly recommend therefore that the product instructions and specifications are first downloaded from our website and properly studied and understood. This knowledge is essential to facilitate a grasp of each engines concept and also provides an overview of the correct peripheral components necessary to complete each engine type.

Conclusion: A set of casings that leaves nothing to be desired. The limits from here on are suspension and brakes, not the engine’s potential.

The following parts are included in the delivery:

• Brake cable stop rear brake, including bolts
• Stop clutch cable, including bolts
• Bolt dust cover
• Precision sleeves for casing halves
• Flywheel cover including bolts
• Pins for brake pads
• Sleeve layshaft, including bolts
• Studs gear selector box
• Studs barrel, including nuts
• Bolts engine casings
• Adaptor barrel studs, including bolts (SIP BFA 200/221 only)
• Instruction

Dimensions of the cylinder openings and crankshaft axis to the gasket surface area distances:

The Best Setup – Our SIP-TIP:

• SIP BFA crankshaft art.-no. 78245800, 78245810 or 78245820 must be used
• The ideal clutch to smoothly deal with the power is the SIP-BFA Clutch (e.g. art.-no. 78245900)
• The Motorino Diavolo Shifter is yet another great part for building a reliable high performance engine (art.-no. 87049300).
• Best combined with the SIP shift pulley (art.-no. 13978640).

Attention: Not all ignitions fit on the housing for the BFA 306, as the transfer ports are very bulky. We offer a modified vape fan (art.no. 51007320), as well as a complete SIP Performance ignition for this engine (art.no. 51007BRA).