【SIP BFA】 ピストン SIP BFA，306用

Φ 78mm
1 piston ring(s)
pin Φ＝18mm
TUNING RACE - for professionals

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As every experienced tuner knows “Nothing beats cubes，except more cubes”.
BFA have taken this wisdom to the extreme and are now producing a complete engine，suitable for Vespa largeframe models，with a cubic capacity of a whopping 306cc！ No engine component is left untouched by this madness！ The design of the casings，cylinder，crankshaft，etc.
were all freshly conceived for the challenges posed by a high-end 306cc motor.
The result raises Vespa tuning to another new level.
Power，torque，and delivery of the available performance are more comparable with that of a modern Motocross motorbike than a humble road-going scooter！
The engine casings of this 306cc BFA motor are produced using completely new die-cast forms and retains the original basic construction and distance between the engine shafts of the original PIAGGIO types.
Around these parameters BFA have created a lot of extra space for expansion.
Enough for a much stronger crankshaft with a longer stroke，the cylinder with a 78mm bore，a broad transfer port layout and thicker casings and shaft support struts for an increased structural stability.
A wonderful example of this is provided by the especially useful massive input shaft mounting.
The distance between the cylinder mounting studs is 100mm x 100mm and the 70mm wide inlet port opening is located directly adjacent to the cylinder base mounting surface and is stretched over both engine casing halves.
Both crankshaft bearings possess an outer diameter of 62mm and the original 613912 PIAGGIO bearings can be used.
On the clutch side the crankshaft is supported by a roller-pin bearing.
25x35x7 ＆ 25x40x7 sized shaft oil seals are used at either end of the crankshaft.
The engine casings come complete with damping rubbers for both the swing-arm pivot and the rear shock absorber mountings but the reed-valve and its housing require ordering separately.
The BFA kit comes with a four-petal reed that already finds use with the QUATTRINI ＆ DEA cylinders.
The short，die-cast manifold provides the fuel mixture over a stuffer into the crankcase with an inner diameter of 40mm and a connection diameter of 45mm.
The central feature of the BFA 306 engine is provided by the totally newcylinder.
Its unusually large capacity is provided by a 64mm stroke and a 78mm bore.
The piston possesses a flat crown and a single piston ring and the cylinder head has an O-ring gasket and is secured with eight bolts.
The spark plug is centrally located.
The exchange of gases through the cylinder is taken care of by five voluminous transfer ports coupled with a double-bridged exhaust port.
The exhaust mounting flange is made of steel，is attached to the cylinder with four bolts and the outer connection diameter is 50mm.
The cylinder mounting studs do not extend to the cylinder head as the cylinder is attached to the casings only at the base.
This feature provided more room for the engineers to develop a more efficient transfer port layout.
The crankshafthas an extremely sturdy construction，with a width across the 102mm diameter webs of 54.4mm.
The forged and polished con-rod has a length of 135mm and the clutch stub is especially solid in appearance.
The clutch is no longer attached conventionally to the crank with a woodruff key assuring correct positioning but is fixed to the crank with a stable cog mechanism.
The flywheel stub employs the usual slot and key method，compatible with most common flywheel mountings.
The clutch，that BFA created for this engine，is attached to the BFA crankshaft with a solidly fixed cog which prevents misalignment through twisting.
It is based on the PX style clutch that they already produce but effectively reverses the operation and basic construction.
This primarily reduces the total mass that rotates with the crankshaft and also improves the clutch plate cohesion，facilitating a smoother overall operation while also eliminating clutch snatch.
The primary drive cog was also custom-developed for this engines clutch.
Its ultra-low profile design not only provides reliable and enduring transmission of power but also frees up essential space for further tuning measures.
This construction trick allows，for example，the inclusion of five friction plates within the clutch.
The clutch cog is attached to the aluminium CNC machined clutch basket with twelve bolts and the inner shaft is provided with a needle-roller bearing，replacing the original-style bronze bush.
The pressure plate also features a bearing mechanism，located around an aluminium rotating centre.
The clutch plates are all made of aluminium and the bottom plate has six spring recesses，similar to the Vespa smallframe clutch design，which can each be equipped with two coil springs within each other.
The delivery includes a straight-cut primary drive cog as well as two special bolts that enable the clutches plates to be replaced while the clutch is still attached to the crankshaft.
All of this fresh technology fits beneath a standard PX 200 clutch cover！
Theexhaust for the BFA 306 has，along with the rest of its major components，also been specifically developed to complement this advanced engine concept.
This not only means that it is perfectly matched to the exhaust flange on the cylinder，but also has carefully calculated dimensions to suit its capacity，port timings and channel cross-sectional areas to produce a strong and harmonious power curve.
The BFA 306 engine and its separate components represent the most exclusive tuning accessories available to increase the performance of traditionally-geared motor-scooters.
This is not necessarily just a referral to the price segment it is found in，but much more the impressive quality of the high-end materials and engineering standards involved in its construction.
The absolute highlight is provided by the potential ‘Warp-speed’ performance that this state-of-the-art technology can supply.
Another master-stroke is that all of these modern components have been assembled within the confines of a Vespa largeframe-sized engine unit！
Conclusion：The finest method of creating a wolf in sheep’s clothing！
306cc/Reinforced casings/5-plate clutch/Reed-valve inlet/78mm bore
SIP-TIP：To perfectly complement the inclusion of a BFA engine in the set up of your scooter do not forget to order a solid set of gear cogs，such as the DRT F1 components.
A modern ignition system (for example a SIP Performance ignition) and a suitably dimensioned carburettor (Keihin PWK 38) are also highly recommended，if not essential！ Don´t forget to order bearings，oil seals and silent rubbers.

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