bgm PRO Touring exhaust system for Vespa Wideframe

The new bgm Pro touring box is a well-camouflaged, high-performance sports exhaust that looks absolutely inconspicuous in the look of the standard exhaust.

The construction of the bgm PRO touring box is designed for maximum compatibility with the cylinder concepts available on the market. A flat cone angle and a moderate resonance length are the main features of the box. Below we show three examples of completely different engines on which we have tested the WF box.

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ACMA V55

with bgm150 cylinder, (Ø57mm) bgm crankshaft (stroke 57mm), Polini CP24 carburetor, bgm Pro Touring exhaust (bgm1015TR)

It's nice to see how early and linear the engine's performance starts and increases with the bgm box. It harmonizes very well with the tame control angles of the bgm150cylinder. Despite the high and early torque, the power is maintained for a long time. This makes the engine very pleasant to drive, as it starts to 'pull' immediately and can also be revved if necessary. An ideal characteristic for a powerful everyday engine.

ACMA

with CC Corsa 160 cylinder (diaphragm-controlled), PHBL 25 carburettor, bmg Pro Touring exhaust (bgm1015TR)

The CC Corsa 160 cylinder is a popular conversion cylinder for all those who want to build a solid but powerful engine based on the original housing. The bgm Touring exhaust also harmonizes very well with the diaphragm-controlled cylinder. Compared to the bgm150, the significantly higher control angle (approx. ÜS125°/AS175°) shifts the peak power by approx. 1000 rpm. The harmonious, hole-free climb offers absolutely stress-free riding, while the rising torque up to the peak provides the sporty 'pull' typical of a two-stroke engine. Here too, the engine can be revved up even further after reaching peak power, e.g. to save a gear change when overtaking quickly.

GS150 engine

with Quattrini M1XL cylinder (diaphragm-controlled for PX125/150 engine), PHBL30 carburettor, bgm Pro Touring exhaust (bgm1015TR)

A special engine based on a Vespa GS150 Wideframe engine case, which has been converted with a diaphragm-controlled Quattrini cylinder for a PX125/150 engine. Combined with a 60mm king shaft, this results in a displacement of 181cc. The engine is installed in a wideframe, which is why the BGM Pro Touring exhaust also met with great interest. The cylinder is unmachined here and runs with timing angles of 124/176. The BGM box delivers plenty of power here too. 21 hp and 22 Nm are quite impressive for a system that is designed purely as a touring exhaust system and does not have a large volume. It may be possible to achieve even more with a smaller steering angle, but for the purposes of this comparison, it is clear that the system can be driven perfectly well even on very sporty engines and still delivers high performance. Here, too, the driving noise is very pleasant, which is why the vehicle owner had the exhaust fitted directly to the vehicle.

DEVELOPMENT bgm Pro Touring box

REQUIREMENTS The aim in developing the bgm wideframe box was to design a robust, quiet, high-torque and powerful exhaust that can be used on as many engine concepts as possible. THE ORIGINAL It took a lot of time and work on the test bench to fulfill these sometimes quite contradictory requirements. At the time the first Vespa engines were designed, there was neither the effective Schnürle reverse scavenging nor a deeper understanding of how to improve the charge exchange in the cylinder with the aid of the exhaust. In principle, the original exhaust of the Wideframe models was therefore never much more than a silencer. It was only marginally involved in engine performance, if at all. It follows that due to the low liter output of the engine (~30hp/l), only a small volume was required for silencing (apart from the fact that in the 1950s the noise development of a 125cc engine was not yet a serious problem in everyday life anyway...). MODERN CONSTRUCTION Nowadays, the volume of an exhaust is not only relevant for sound insulation, it also has a significant influence on performance and its progression. Today's designs use a suction diffuser, the exhaust itself is then the 'virtual' counter-cone. A higher power output and lower noise level can therefore be achieved with a larger volume. SPACE CONDITIONS The space for a larger exhaust on the Wideframe models is limited by the surrounding bodywork and is therefore not as variable as on the PX models, for example. Anyone who has previously installed a more powerful engine therefore usually resorted to an adapted PX exhaust system. Although these have more volume, they are positioned transversely under the vehicle and considerably reduce the ground clearance. Visually, they only match the beautiful lines of the now very valuable Wideframe models to a limited extent. For this reason, the BGM Wideframe exhaust system was developed with a view to achieving a look that is close to the standard version. VOLUME VS. NOISE The available exhaust volume is required both for power delivery and for silencing. The more volume is used for power delivery, the more power/torque can generally be generated at the expense of noise. To avoid being seen as a potential disruptive factor in today's sometimes somewhat hysterical environment, low noise development was an important factor in the development phase. We have succeeded in combining high performance with a pleasant sound that is also suitable for older vehicles. Even with engines with almost four times the liter output of the original engine, the exhaust is very pleasant to drive on long journeys. QUALITY The bgm Pro Touring Box has a very solid mechanical design and is manufactured in Europe (Spain) to a very high quality standard.

about the bgm Wideframebox


CONCLUSION: The development goals have all been realized and result in an exhaust that is excellent for everyday use. It offers a superior power output with a pleasant driving noise combined with high manufacturing quality.