BGM PRO Lay Shaft for Vespa Largeframe PX, Rally, T5, Cosa, LML (2-Stroke)

Modern cylinders such as Malossi MHR, Quattrini M244 or Pinasco 251 have raised the performance and torque levels of Vespa Largeframe engines to a completely new level.
Accordingly, the used gearbox components must be correspondingly stable.

MATERIAL QUALITY
The BGM PRO lay shafts are manufactured from high-quality 21NiCrMo2 (1.6523) case-hardened steel, the surface of which is finally hardened to 62HRC. The high core strength of the material (900N/mm²) enables maximum load transfer (high engine torque), and the very good toughness (ductility) ensures a very high resistance to peak loads. The final hardening (heat treatment) hardens the surface to a depth of 0.6-0.8mm, resulting in maximum wear protection.

• MATERIAL: 21NiCrMo2 (1.6523)

• HARDNESS: 62HRC

• RATIOS GEAR 1-4:

• BGM6504: 12-13-17-21 (Standard Ratio)

• BGM6505: 12-13-16-19 (short third, extra short fourth gear)

• BGM6506: 12-13-17-20 (short fourth gear)

MAXIMUM STABILITY THROUGH CORRECT GEAR RATIO
The ratio of the lay shaft has, in addition to a perfect adaptation of the gearbox to the engine characteristics, another important aspect.
The fewer teeth a gear pair has with the same axle distance, the more stable it is (the teeth become wider).
For this reason, a motor with a high torque, e.g. no 'short' fourth gear with 36 teeth (original only with 125cc!) should be used. Here the tooth flanks are narrower than with the 35 teeth wheel of the 200ccm models.

BGM6505: 12-13-16-19 (short third, extra short fourth gear)
Another expansion stage is the lay shaft with 12-13-16-19 teeth. Here the third gear is also one tooth shorter, the fourth gear already two teeth 'shorter'. This means that the gear jumps from 2-3 and 3-4 are significantly shorter than with the factory ratio of Piaggio. This ratio is ideal when a very long primary reduction (e.g. BGM 25/62) is to be used in a high-torque engine or the engine is very rev-happy and a short gear stage is needed to always stay in the power band of the engine.

BGM6506: 12-13-17-20 (short fourth gear)
In order to still achieve a better gear engagement between the third and fourth gears while maintaining maximum stability, we recommend using the lay shaft with a 12-13-17-20 ratio. Here the lay shaft has one tooth less for the fourth gear (20 teeth instead of 21 teeth = more stable) and can therefore be combined with the original fourth gear of the 200ccm models with 35 teeth (= more stable). As a result, the fourth gear is again slightly shorter than with the 21/36 pairing (approx. 2-3km/h) while simultaneously increasing the load capacity. This lay shaft is therefore ideal for engines with a lot of torque and a linear power curve. The engine can then be sufficiently long reduced on the primary side, the gear jump from three to four remains exactly fitting.

ACCESSORIES
As an ideal combination for a powerful engine, we recommend the perfectly matched clutch and primary parts from BGM PRO. For powerful engines, we exclusively recommend the use of straight-cut clutches and primary drives. These are structurally capable of withstanding the high loads and, due to their careful manufacture, are not louder than the helical gearbox parts. The springs of the primary internal shock absorbers are also adapted to the high torques. The stiffer springs prevent the shock absorber from 'blocking', effectively keeping peak loads away from the gearbox.The BGM PRO lay shafts are designed for use with BGM PRO or original Piaggio gears. The BGM PRO lay shafts are designed for use with BGM PRO or original Piaggio gears.

About the Manufacturer BGM

BGM is a leading brand for high-quality spare parts and accessories for scooters, motorcycles and classic Vespa models, which stands for quality, precision and innovation. With a uncompromising “Made in Germany” philosophy, BGM develops durable products in collaboration with leading engineers and under strict quality controls. Whether restoring vintage vehicles or tuning modern scooters – BGM is the first choice for demanding drivers. Thanks to first-class processing and a broad range, BGM offers ideal solutions for performance, everyday use and individuality.