BGM PRO Primary Spring 50 N/mm – Enhanced Shock Absorption for Vespa Largeframe
More power reserves for the primary drive—now at an attractive special price. The BGM PRO shock absorber spring with a spring rate of 50 N/mm is suitable for classic Vespa large-frame engines ranging from 80 to 150 cm³, as well as moderate 177-cm³ touring and sport engines.
Its reinforced spring characteristics are particularly beneficial under conditions of increased engine torque and heavy load changes. This makes it a practical upgrade option when overhauling compatible primary drives.
The advantages at a glance
- 50 N/mm spring rate: Stiff spring characteristics for higher loads
- Ideal for touring tuning: Also suitable for moderate 177-cm³ engines
- Controlled spring movement: Less spring compression under the same load
- For classic large-frame motorcycles: Compatible with corresponding primary drive designs
- Attractive special price: Reinforced BGM PRO spring at a particularly low price
Why a reinforced primary spring makes sense
Shock absorption in the primary drive compensates for torque fluctuations in the single-cylinder engine and reduces the direct transmission of load spikes to the transmission.
The springs are subjected to heavy stress, particularly when accelerating from low RPMs, during gear shifts, or with abrupt changes in throttle input. As engine power and torque increase, these stresses continue to rise.
The BGM PRO spring, with a spring rate of 50 N/mm, offers correspondingly high resistance to compression. As a result, it compresses less under the same load than a softer spring.
This is particularly beneficial for engines whose stock shock absorption reaches its limits due to higher torque loads. The reinforced spring can help prevent premature full compression.
Also for moderate 177-cm³ touring engines
A classic PX125 or PX150 engine with a 177-cm³ cylinder often develops significantly more torque than in the original stock configuration.
Especially for popular touring setups with DR177, Polini177, or comparable cylinders, it therefore makes sense to check the primary rebound damping.
The BGM PRO spring with 50 N/mm offers a reinforced alternative for this purpose, provided the existing primary drive has the appropriate spring mount.
For very high-performance race engines or primary drives with multi-stage spring arrangements, however, we recommend a shock absorber repair kit that is fully tailored to the specific load.
Which primary drive is suitable?
The decisive factor for use is not just the displacement, but the design of the primary drive.
The BGM0196F50 is designed for the corresponding large-frame primary drive configuration with the following arrangement:
- Alternator side: Offset cover plate in the area of the shock absorber springs
- Clutch side: Flat cover plate
- Spring arrangement: Use without additional narrow inner springs
Before installation, ensure that the existing spring mount and the design of the cover plates are compatible with this version.
Important: Do not combine with the inner springs from the PX200
Various 200-cm³ primary drives use additional narrow inner springs, which are positioned inside the larger outer shock absorber springs.
The BGM0196F50 has a smaller inner diameter than the outer springs intended for this purpose. The narrow inner springs of the 200-cm³ version therefore do not fit inside.
This spring is designed for use without these additional inner springs. If you wish to overhaul a primary drive with nested outer and inner springs, you will need the appropriate springs or a corresponding primary drive repair kit.
Important: The existing spring configuration must not be altered solely based on the vehicle model. The actual design of the installed primary drive is the determining factor.
Technical Data
| Feature |
Version |
| Manufacturer | BGM PRO |
| Item Number | BGM0196F50 |
| Component | Primary spring / shock absorber spring |
| Version | Reinforced |
| Spring Rate | 50 N/mm |
| Vehicle range | Vespa Largeframe 80–150 cm³ |
| Tuning application | Moderate 177-cm³ touring engines |
| Cover plate (Lima side) | Removed |
| Cover plate, clutch side | Flat |
| Additional 200-series inner springs | Not compatible |
Compatible Vehicles
For compatible Vespa large-frame primary drives, for example:
- Vespa PX80 / PX125 / PX150
- Vespa Cosa 125
- Vespa T5 125
- Vespa GT125 / GTR125 / TS125
- Vespa 125 Super (VNC, starting with chassis number 11001)
- Vespa GL150 / Sprint / Sprint Veloce
- Vespa 150 Super (VBC)
- Vespa VBB with matching primary drive
- Other large-frame models with compatible spring mounts
For models such as the GS160 or SS180, as well as for engines that have already been overhauled or modified, the actual primary drive configuration must be checked particularly carefully before ordering.
Installation Instructions
To replace the shock absorber springs, disassemble the primary drive. While doing so, also inspect the spring mounts and cover plates for wear, deformation, and cracks.
- Compare the design of the cover plates and spring mounts with the intended configuration
- Do not combine with any additional narrow inner springs with part number BGM0196F50
- Use springs of the same design in accordance with the intended configuration
- Properly install the cover plates and fasteners using suitable new parts
- After reassembly, check the function and free movement of the shock absorption mechanism
Scope of Delivery
- 1 × BGM PRO primary spring, reinforced, 50 N/mm
Additional springs, cover plates, and fasteners are not included.
Frequently Asked Questions (FAQ)
Is the spring suitable for a 177-cm³ engine?
Yes. The reinforced 50 N/mm spring is also a good choice for moderate 177-cm³ touring engines. A compatible primary drive—without the incompatible additional inner springs—is required.
How can I tell if the primary is the right one?
The intended primary drive has a stepped cover plate on the alternator side and a flat cover plate on the clutch side. Additionally, the spring mount must be compatible with the BGM0196F50.
What does a spring rate of 50 N/mm mean?
With a linear spring characteristic curve, the force required to compress the spring increases by 50 newtons for every additional millimeter of spring travel. As a result, the spring responds to a given load with a correspondingly defined compression.
Can I use the inner springs from a PX200?
No. The inner diameter of the BGM0196F50 is too small for the additional narrow inner springs of the 200-cm³ primary. This combination is therefore not possible.
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