BGM PRO Touring Evo Crankshaft – 57 mm stroke, 105 mm connecting rod, rotary valve
The BGM PRO Touring Evo Crankshaft BGM031120G is designed for high-performance, durable Vespa PX125/PX150 rotary valve engines. It combines a 57 mm stroke with a 105 mm connecting rod, forged crankpin shoulders, high-quality connecting rod bearings, and the latest Touring Evo joining technology at the crankpin.
Touring Evo represents the consistent further development of the well-known BGM PRO Touring series. Particular emphasis is placed on the connection between the crankpin and the crankpin shoulders: In addition to a precisely defined press fit, there is an additional chemical lock using high-strength anaerobic Loctite bonding adhesive. This increases the torsional stability of the crankshaft under high loads.
BGM PRO Touring Evo
57 mm standard stroke
105 mm connecting rod
Rotary valve
Spliced forged connecting rod
Chemically treated connecting rod journal
Key advantages
Touring Evo: Advanced manufacturing and joining technology
Forged crankshaft journals: a robust foundation for high-performance engine designs
Copper-plated forged connecting rod: robust connecting rod design with a distinctive copper surface
High resistance to twisting: precise press fit and additional chemical crankshaft journal locking
Optimized connecting rod bearing lubrication: large lubrication slots and additional lateral pockets
Tuning-friendly intake layout: practical rotary valve timing instead of extremely long intake duration
Touring Evo – the current stage of evolution
The designation “Touring Evo” denotes the current stage of development within the BGM PRO Touring crankshafts. Over the years, material selection, machining, press fit, and assembly processes have been consistently refined.
What is crucial here is not only the material quality of the crankshaft journals but, above all, the connection at the crankpin. The mechanical press fit is additionally secured with a high-strength anaerobic Loctite bonding adhesive. This additional chemical lock complements the press fit and increases protection against crankshaft half-shafts twisting under high torques and rapid load changes.
What “Touring Evo” Means Technically
Forged crankshaft journals: robust base structure
Defined press fit: precise mechanical connection between the crankpin and the crank arms
Loctite bonding: additional chemical securing of the joint
High resistance to twisting: for high-performance, high-torque street engines
Copper-plated, drop-forged connecting rod
The connecting rod in this Touring Evo version features the characteristic copper-plated surface. At the same time, the connecting rod is drop-forged according to BGM PRO specifications. These two features are not mutually exclusive: the copper plating refers to the surface treatment, while the forging refers to the manufacturing of the connecting rod’s base body.
With a connecting rod length of 105 mm, this version corresponds to the geometry intended for the PX125/PX150. Combined with a 57 mm stroke, this results in a crankshaft assembly tailored to this engine type.
57 mm standard stroke – a straightforward basis for powerful street engines
With a 57 mm stroke, this version matches the stock-like stroke dimension of the classic Vespa PX engines. This makes it particularly suitable for cylinder and engine designs that are structurally optimized for the standard stroke.
The advantage lies in a straightforward engine geometry: additional stroke does not need to be compensated for via head or foot clearances. At the same time, high-performance tuning cylinders also benefit from the robust Touring Evo construction and the rotary valve profile designed for tuned engines.
57 mm – when a standard stroke is specifically desired
Production-spec stroke of 57 mm
Ideal for cylinders designed for standard stroke
No additional long-stroke compensation required solely due to the stroke dimension
Excellent foundation for powerful touring and street engines
Intake layout for high-performance rotary engines
Compared to a stock crankshaft, the BGM PRO Touring Evo features an intake layout that is significantly more tuning-friendly. On a typical PX engine block, the rotary valve closes at approximately 65° after TDC with this crankshaft family. The actual value depends on the specific engine block and its intake port.
If the intake port is machined appropriately on the opening side, approximately 110–115° before TDC has proven to be a practical starting point for many street and touring setups. This results in an intake duration that is easy to tune without unnecessarily forcing the engine to operate with extremely long valve timing.
Always measure intake timing on your own engine case
The angles specified are guidelines. Vespa engine cases differ in their intake ports, and existing modifications also alter the actual valve timing. For a precise engine build, the intake start and intake end should therefore always be measured on the installed engine.
Sophisticated Bearing and Lubrication System
The lower connecting rod bearing is lubricated via two large lubrication slots and a total of four additional lateral pockets. The SSC racing bearing and the lateral thrust washers form a bearing assembly designed for high continuous loads.
The upper connecting rod bearing is supplied via two lubrication holes. An INA piston pin bearing is included in the scope of delivery.
Proven for high-performance street engines
The BGM PRO Touring Evo is designed for engines that are meant to perform not only on the test bench. Forged components, sophisticated bearing arrangements, and the chemically treated connecting rod journal connection create a robust foundation for powerful touring, street, and sport setups.
Rather than focusing on a rigid power limit, the Touring Evo centers on the field-proven design of the entire crankshaft assembly. Especially with high-performance engines, the flywheel mass, ignition, clutch, and RPM range should be sensibly coordinated.
Practical Tip: Shaft Seal
The oil seal seat on the BGM PRO shaft is wider than on many stock shafts. This allows for the use of a double-lip FKM oil seal (24×35×7), such as the one used in the Gilera Runner.
Technical Specifications
| Manufacturer | BGM PRO |
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| Series | Touring Evo |
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| Item Number | BGM031120G |
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| Engine Type | PX125/PX150 |
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| Intake Principle | Rotary vane |
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| Stroke | 57 mm (standard stroke) |
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| Connecting rod length | 105 mm |
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| Piston pin | Ø15 mm |
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| Crank arms | Drop-forged |
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| Connecting rod | Drop-forged, copper-plated surface |
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| Lower connecting rod bearing | SSC racing bearing with optimized lubrication |
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| Upper connecting rod bearing | INA piston pin bearing included |
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| Connecting rod journal | Precision press fit with additional chemical Loctite locking agent |
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| Typical intake valve closure | Approx. 65° after TDC, depending on the engine block |
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| Practical value for intake start | Approx. 110–115° before TDC as a possible starting point |
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| Compatible | Vespa PX125, PX150 |
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Installation and Setup
Check the crankshaft for full freedom of movement before final assembly
Inspect the rotary valve sealing surface and the intake port of the engine housing
Measure the intake valve timing on the specific housing
For long-stroke variants, determine the cylinder position, compression edge, and timing angle appropriate for the cylinder being used
Select shaft seals and bearings appropriate for the engine type and install them properly
Match the flywheel, clutch, and ignition system to the engine’s power output and intended application
Conclusion
The BGM PRO Touring Evo BGM031120G combines proven PX geometry with consistently refined manufacturing. Forged crankshaft journals, the copper-plated forged connecting rod, the sophisticated bearing arrangement, and the additional chemical protection of the crankpin form a robust crankshaft assembly for high-performance Vespa engines in continuous use.
The “Evo” designation clearly indicates the technical advancement: The focus is not on a cosmetic model update, but rather on the further-developed joining technology and high resistance to twisting.
FAQs about the BGM PRO Touring Evo BGM031120G
Touring Evo denotes the current stage of development for the BGM PRO Touring crankshafts. This includes advanced manufacturing processes, a precise press fit on the crankshaft journal, and additional chemical locking with high-strength Loctite bonding adhesive.
Yes. According to BGM PRO specifications, the connecting rod is drop-forged. The visible copper plating is a surface treatment and does not conflict with the forged construction of the connecting rod’s base body.
On a typical PX engine block, this camshaft family closes at approximately 65° after TDC. The actual value depends on the intake port of the block being used. A starting point of approximately 110–115° before TDC has proven effective for a machined intake port.
The crankpin is mechanically connected to the crankcase halfs via a precise press fit and is additionally chemically secured with high-strength anaerobic Loctite adhesive. This combination is a central component of the Touring Evo assembly technology.
57 mm corresponds to the standard stroke close to stock specifications. 60 mm is a long stroke and increases the displacement while maintaining the same bore. In addition, the piston position changes, which—depending on the cylinder—may require adjustment via gaskets or spacers or can be utilized for valve timing adjustment.
Yes. The Touring Evo design is specifically engineered for high-performance, high-torque street engines. Forged components, high-quality bearings, and the chemically sealed crankpin connection provide a robust foundation for this.
Due to the wider shaft seal seat, a double-lip FKM shaft seal in size 24×35×7 can be used. It is crucial that the seal fits the specific engine housing and the chosen mounting configuration.
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