The BGM 190ccm tuning kit consists of two reliable components: The BGM177/190 cylinder, which has been proven a thousand times over, and the BGM Touring crankshaft with extended stroke (60mm instead of 57mm).
Together they form an extremely harmonious unit which is very powerful on the one hand and ultra-reliable on the other. The BGM cylinder was designed for the optional use with a long stroke shaft. The longer stroke of the BGM crankshaft is compensated by a head gasket spacer included in the set. This results in ideal cylinder steering angles for a powerful sports tourer.
The kit can be installed as a pure plug-in tuning, i.e. without milling/adaptation work on every PX125/PX150 engine (and identical in construction as e.g. LML or older Vespa engines like Sprint150 Veloce, GTR125). With a suitable exhaust, such as the perfectly harmonizing BGM BigBox Touring, you can easily exceed the performance of a Vespa PX200. A full 13-15HP are already available at the rear wheel (original PX125 ca.5-6HP) with which the scooter already accelerates very quickly and, depending on the selected gear ratio, drives well over 100km/h.
If you want to get more power right from the start, you can increase the performance with quite simple means. 16-19hp are no problem by simply adjusting the overflow channels (see video) and the intake including carburetor of the 200ccm models (SI24/24E). The engine remains as reliable as a production engine because the speed remains at the level of the production engine. The quality and grade of the materials used also allow a continuous full throttle operation without any problems.
The consumption remains very moderate for the performance values and ranges between 3.5-4.5 litres.
The noise level also remains pleasantly low, also a merit of the moderate engine speed level.
For engines which are mainly used in the city and overland, an extension of the transmission ratio to 23 teeth (23/68= 2.95) by means of a clutch pinion is sufficient.
If you have a high top speed in mind or like to drive on the motorway and don`t want high revs, you can switch to a completely different primary transmission ratio. We recommend the BGM primary gear for the PX200 with 65 teeth or 64 teeth.
This also fits on the auxiliary shaft of the PX125/150 models. Together with a matching BGM coupling pinion with 22, 23 or 24 teeth, you have the full range of possible gear ratios to choose from. A 23/64 primary has proven to be a good choice.
CYLINDER
The bgm PRO 177 cylinder is a hard ceramic coated aluminium cylinder with 63mm bore. The coating (nickel silicon carbide) ensures an extremely hard and durable raceway. The piston has a high silicon content. Therefore it has a lower thermal expansion, is more wear resistant and thermally very stable. Two 1mm thick piston rings minimize friction and thus increase power and speed stability. The channel layout of the cylinder with four main transfer ports and two boost ports is designed for high pressure from the lower speed range.- Cylinder material: aluminium
- Raceway: coated with nickel-silicon carbide
- Bore: Ø 63mm
- Displacement 60mm stroke: 187 ccm
- Piston: cast iron piston with high silicon content and two 1mm steel piston rings
- Recommended pinch point: 0,8- 1,2mm
Steering angle
- 60mm stroke: overcurrent 123°, outlet 173° (with foot seal 0.2mm, head spacer 1.5mm)
The overflow channels at the cylinder base have a sprue. Thus the channels on the cylinder correspond to those on the engine housing. The sprue can easily be removed to use the complete cross section of the channels.
The cylinder head is milled from a solid CNC. The combustion chamber is sunk 4 mm deep into the cylinder for perfect centering.
This also makes it much easier to adjust the squeezing edge and the sealing is always guaranteed. A thread for mounting a temperature sensor is provided in the middle.
HUB 60MM | ||
QC | combustion chamber | Compression |
0.8mm | 18.38 cc | 11.2 : 1 |
0.9mm | 18.69 cc | 11.0 : 1 |
1,0mm | 19.01 cc | 10.8 : 1 |
1.1mm | 19.32 cc | 10.7 : 1 |
1,2mm | 19.63 cc | 10.5 : 1 |
NOTE: Not suitable in conjunction with an Elestart polewheel. For models with an electric starter, remove the E-Start sprocket (the sprocket is shrunk on) or use a pole wheel without sprocket (see accessories).
CURVEL SHAFT
MATERIALThe bgm PRO Touring crankshafts are forged. The material is more dense, thus better dissipating the heat and is therefore more resistant to distortion. Besides the crank webs, the connecting rod is also forged and then CNC machined.
STORAGE
The lower connecting rod bearing is lubricated via two large lubrication slots and a total of four additional pockets on the side. The SSC race bearing and the lateral thrust washers provide a solid bearing. Lubrication of the upper connecting rod bearing is done via two lubrication holes. The INA piston pin bearing is supplied with the crankshaft.
INLET ANGLE
The bgm PRO Touring wave has a much better intake layout compared to many other racing waves. For tuning cylinders the standard shaft with its very short intake time does not come along. The bgm PRO shaft, on the other hand, closes on a PX motor housing approx. 58° after top dead center (depending on the motor housing, this differs ex works). The motor can be well tuned with these control angles. TIP: If the inlet is machined so that the crankshaft opens the inlet slot earlier, additional power can be gained. A good value is about 120° TDC.
CONCLUSION
The combination of bgm PRO crankshaft and bgm Pro cylinder is a good decision in all respects. Highest quality in every component. Precision in manufacturing, materials used provide high and durable performance. All this at an unbeatable price-performance ratio!
