Racing Cylinder SIP BFA 306 cc

The most powerful cylinder kit with the largest engine capacity for traditional Vespa Largeframe models: The 306ccm by BFA Motori

A lack of engine capacity can be compensated by numerous technical tricks and improvements. If the engine makes use of these tricks and improvements already finding more power becomes a real challenge. The original Vespa engine was never meant for maximum power, and, let’s face it, it’s a bit dated too. Hence it does not exactly lend itself for high end tuning. The lack of “real estate” for decently sized ports could be compensated for with a larger engine capacity, and limitations in bore and stroke size wouldn’t be a problem if it were possible to improve the layout of the barrel by using a modern port arrangement. The best solution obviously would be a modern, large capacity engine. A pipedream? Actually, no!

With designing the SIP BFA 306cc Racing Kit BFA has made a dream come true; a dream in which there hardly seem to be any limits to build a large capacity two-stroke engine. A dream with 306cc and a thoroughly modern cylinder layout whose full potential has yet to be exploited.

• 306ccm engine capacity
• Modern port layout with huge transfer port area and a triple exhaust port
• Cylinder head bolted down with 8 bolts, centre spark plug design
• Short cylinder studs which do not interfere with the port layout

Layout of the SIP BFA 306 cylinder kit

The engine capacity, which, for a geared Vespa, is unprecedented, is the result of 64mm of stroke and a bore of 78mm. The piston features a flat crown and one piston ring. The cylinder-head bolts down with 8 short bolts, with a central spark plug, and it seals with an O-ring. The cylinder itself has 5 transfer ports and one main exhaust port with two sub exhaust ports. The exhaust flange bolts to the cylinder with 4 bolts. The outside diameter of the exhaust stub is 50mm. The barrel is held down on the crankcase with four short bolts, unlike the long studs of the original type cylinders. As a result BFA could start the barrel design on a clean sheet, without a need to design ports around limiting cylinder studs.

With preconditions like these the sky is the limit. Transfer port timing still are in the ballpark of a fast road-touring engine. You could either build a low revving engine with tons of torque and a wide powerband, or you could opt for an engine happy to rev, pushing out in excess of 50 BHP or 60 even. Whatever rocks your boat is on the table for you to choose.

Conclusion: The ideal Vespa kit, possibly the ultimate happy ending to all teenage dreams.

A list of technical details:

• Plated aluminium barrel
• 78mm bore
• Engine capacity of 306 cc
• Stroke 64mm
• 5 transfer and 3 exhaust ports
• Flat crown piston with one 1mm piston ring
• 8 bolt cylinder head with centre spark plug
• Includes 2 base gaskets and one O-ring for the cylinder head

Our recommendation - SIP-TIP:

• Only fits crankcase art.-no. 78245500 and crankcase art.-no. 78245800
• Best combined with T5 cylinder cowl art.-no. 23321700 and flywheel cover art.-no. 23328500
• Order the correct long thread spark plug such as DENSO IW 31 art.-no. 88571000 or NGK BR10EIX art.-no. NGKBR10EIX
• Run with fully synthetic two stroke oil, SIP Race art.-no. 14440000 or MALOSSI 7.1 Racing art.-no. 76823000