Cylinder -bgm PRO 177 ccm- Vespa PX125, PX150, Sprint150, GTR125, TS125, Cosa125, Cosa150 Here we want to introduce you to the new BGM177 cylinder which will be available from April 2016.
First video BGM177 - the 177cc cylinder for Vespa
We showed the cylinder for the first time at Scooterists Meltdown. The new online scooter magazine SLUK interviewed Philipp and created an exclusive video about our new cylinder:
Suitable for all Vespa 125 / 150 Largeframe engines with 3 overcurrent channels. This includes the :
Vespa PX125,
Vespa PX150,
Sprint 150Veloce,
Vespa GTR125,
Vespa TS125 and the
Cosa 125/150 models.
High-torque and reliable aluminum cylinder
With the BGM177, we provide you with a high-torque and reliable companion. Many ideas have gone into the design of the cylinder so that you can use it in the widest possible power range.
Like all modern cylinders, the BGM177 is made of aluminum. This has the advantage of very good heat dissipation, which benefits durability, consumption and performance. A cast aluminum piston with two piston rings works in the extremely wear-resistant nickel-silicon-carbide-coated cylinder bore.
Very light piston
Due to the design and the high silicon content in the material, the piston can be kept very light at 193 grams with high thermal and mechanical stability. This benefits the ease of rotation and smooth running. The 1 mm thick piston rings are produced by a renowned manufacturer in Italy, which also supplies leading piston manufacturers such as Vertex and Meteor with high-quality piston rings. The slim rings minimize friction and therefore increase performance. They also make it easy to widen the exhaust port window. The piston pin has a biconical design, i.e. it is thinner at the ends than in the middle. This further helps to reduce the weight of the moving masses.
Aluminum cylinder with ceramic coating and large transfer ports
In the cylinder, the large channel surfaces and the large volume of the transfer ports offer the best basic prerequisites for a wide-ranging performance characteristic and an early onset of torque. The BGM177 can be combined with simple standard components such as the original SI20 carburetor and an original exhaust. This means that the BGM177 already offers a significant increase in performance. The modern design of the cylinder helps it to achieve very low consumption values with high torque from the lower rev range.
Cylinder with great tuning potential
If you are looking for more power, the BGM177 offers sufficient potential and possibilities to further increase performance with little effort. The cylinder responds very well to a larger carburetor and a supporting exhaust system, such as the bgm BigBox Touring exhaust system. The overflow ducts in the cylinder base can be extended very easily. The two large overflow ducts on the left and right are only covered by a small sprue in this area. These can easily be opened with a small hand cutter. This means that either the cylinder can be adapted to an already reworked engine housing or the full channel cross-section can be transferred to an engine housing.
CNC-milled cylinder head
The CNC-milled cylinder head has many cooling surfaces and the clearance in the center of the cylinder head means that as little heat as possible is trapped above the combustion chamber. There is also an opportunity to fit a temperature sensor in the clearance. The temperature can be reliably measured this close to the combustion chamber. The usual methods, such as mounting a temperature sensor with an adapter ring under the spark plug or screwing it to the outside of a cooling fin via a thread, do not provide any useful values. They only allow you to judge how warm the cooling air is near the spark plug or how warm the cylinder head gets on the outside of the cooling fin - in our opinion, these positions are simply unsuitable for reliably determining a temperature value. For this reason, bgm uses positioning very close to the combustion chamber.
Combustion chamber for a wide power spectrum
The combustion chamber geometry is designed for a wide power spectrum. The shape of the combustion chamber calotte also allows the use of strong resonance exhaust systems without any problems if the crushing edge is adapted accordingly. On a 57 mm stroke with a touring or box exhaust, the pinch point can be adjusted to 1 mm using the enclosed gaskets. If the cylinder is operated with a resonance exhaust and 60mm stroke, we recommend that you start with the pinch point at 1.2mm.
Timing 57mm
On an engine with 57mm stroke, you will achieve the following values with a pinch point of 1mm:
Compression ratio 10.3:1
Overflow angle 118°
Exhaust angle 171°
The long length of the cylinder allows the cylinder head to be centered in the cylinder bore with a 4mm thick shoulder. Thanks to the shoulder, the cylinder head gasket is still perfectly centered even if the stroke is changed and cannot protrude into the combustion chamber. If the stroke is changed to 60mm, the cylinder can also be raised further depending on the planned engine concept in order to achieve significantly larger overflow angles.
Timing 60mm
On an engine with 60mm stroke, the following values are achieved with a 1mm pinch point:
Compression ratio 10.8:1
Overflow angle 123°
Exhaust angle 173°
The exhaust width is 42mm (66%) and therefore offers good conditions for a free-revving engine even at short head angles.
BGM177 vs PX 200 12PS
Plug & Play with lots of power
Here is a comparison between a BGM177 and a standard Rally200 with a 12PS Piaggio cylinder (comparable to a Vespa PX200 GS). The BGM177 cylinder is unchanged in this test and is fitted to a Sprint Veloce engine. The intake, the crankshaft and the channels in the engine have not been modified. Only an SI24 carburetor from the 200cc models was fitted without adjusting the carburetor sump or the engine housing, and combined with a BGM BigBox Touring. The jetting is very much based on the original 200cc configuration: Main air correction jet: 160 Mixing tube: BE3 Main jet: 125 Secondary jet: 55/160 Air filter: Standard (without additional holes) The pre-ignition was set to 19° v.Ot. The wide power band (smooth lines) and the high available torque (dotted lines) from idle speed can already be seen very clearly on this engine, which has not been further optimized.
Parameters
BGM177
PX 200 12HP
Power output
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Torque
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In the next article, we will look at increasing the performance of the cylinder. An LML diaphragm engine will serve as the basis for this.
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Like all modern cylinders, the BGM177 is made of aluminum. This has the advantage of very good heat dissipation, which benefits durability, consumption and performance. A cast aluminum piston with two piston rings works in the extremely wear-resistant nickel-silicon-carbide-coated cylinder bore.
