Crankshaft - POLINI Racing (rotary valve) Stroke=60mm, Connecting rod length=127mm - Vespa PX200, Cosa 200 - used with Polini 244 cylinder (P1400241)

POLINI Racing Crankshaft 210.0095 – 60 mm stroke and 127 mm connecting rod

The POLINI Racing Crankshaft 210.0095 was developed specifically for the new POLINI 244-cm³ cylinder 140.0241. With a 60 mm stroke and an exceptionally long 127 mm connecting rod, it forms the design foundation for the new Ø72 mm Largeframe concept.

POLINI explicitly specifies this crankshaft for the 244-cm³ cylinder. It is therefore not simply another 60-mm long-stroke crankshaft for the PX200, but rather part of a finely tuned system comprising cylinder geometry, connecting rod length, porting layout, and clutch connection.

POLINI Racing Rotary valve 60 mm stroke 127 mm connecting rod for POLINI 244 Special clutch mount

Why a 127-mm connecting rod length?

The 127-mm connecting rod is the key to the new POLINI 244 concept. A classic PX200 engine uses significantly shorter connecting rod geometry. The extra-long connecting rod allows the cylinder to be mounted higher and the overflow system to extend further into the cylinder.

This enables the large 72-mm-diameter cylinder design without requiring a traditional cylinder base that protrudes far into the engine case. At the same time, however, one thing is clear: A standard 60-mm PX200 crankshaft with a short connecting rod cannot replace the POLINI 244.

Rotary-valve crankshaft

The 210.0095 is designed as a rotary-valve crankshaft. It is therefore intended for engine blocks in which the intake is still controlled via the sealing surface in the crankcase and the crankshaft’s control shoulder.

POLINI does not specify exact intake valve timing in the installation instructions published for the cylinder. Therefore, the actual intake timing should be measured during engine assembly and adjusted to match the carburetor, exhaust system, and desired performance characteristics.

Clutch-Side Teeth – Not a Standard PX Clutch Mount

The most striking design feature of the 210.0095 is located on the clutch side: Instead of the standard PX clutch connection, the shaft has a toothed section.

The POLINI installation manual specifically lists the toothed clutch hub 230.0506 for this purpose. This hub connects to the POLINI HT Clutch. The official POLINI catalog lists 230.0506 as a toothed clutch hub for the Vespa PX’s HT Clutch.

HT Clutch as the Intended System

The POLINI HT Clutch operates differently in design from a classic PX clutch: in this design, the section connected to the crankshaft is constructed as an inner hub. The toothed hub 230.0506 specifically provides the interface to the new crankshaft for this purpose.

POLINI offers the HT Clutch series with various primary sprockets and configurations. When assembling the engine, therefore, not only the clutch but also the desired primary gear ratio must be taken into account.

Does the engine case need to be bored out for the crankshaft?

The current POLINI assembly instructions for the 244-cm³ cylinder do not require separate boring of the crankcase for the crank journals of the 210.0095. Instead, the manual describes the necessary adjustments to the clearance areas of the crankcase, base gasket, and cylinder.

Regardless, during every rebuild, the crankshaft’s full freedom of movement within the specific engine crankcase should be checked before final assembly.

Crankshaft housing machining is nevertheless part of the POLINI 244 rebuild

The long crankshaft and the cylinder design do not eliminate all machining steps. For an original PX200 engine housing, POLINI explicitly requires that the overflow ports be adapted to the contour of the cylinder base gasket. In addition, the base gasket and cylinder are machined to fit in the relevant area.

Even with the POLINI engine case, the transitions from the transfer ports to the cylinder head gasket must be adjusted. The crankshaft itself is thus part of a system that requires careful engine assembly and precise flow optimization.

Alternative to the POLINI system: BGM PRO BGM031128G

If you do not wish to install the POLINI 244 cylinder with the special toothed POLINI clutch connection, the BGM PRO crankshaft BGM031128G is a very suitable alternative.

The BGM crankshaft also has a 60 mm stroke, but uses a 128 mm connecting rod —which is 1 mm longer than the POLINI 210.0095. On the clutch side, it features a conventional PX stub. This leaves the choice of clutch system open, allowing the use of standard, compatible PX clutches with a conventional mounting.

128-mm connecting rod for the BGM crankshaft: additional freedom in valve timing angles

The additional connecting rod length does not change the stroke, but rather the geometric position of the piston relative to the cylinder. Through a targeted combination of foot spacers and, if necessary, head spacers, the cylinder can be positioned differently with the BGM031128G.

This allows the valve timing layout of the POLINI 244 to be more precisely tailored to the desired engine configuration. Depending on the spacer configuration, intake and exhaust valve timing angles can be adjusted without relying on the special POLINI gear teeth on the clutch side.

Technical Specifications

Installation Instructions

Conclusion

The POLINI Racing 210.0095 is the central component of the new 244-cm³ system. A 60-mm stroke and 127-mm connecting rod length enable the unique cylinder geometry of the 140.0241 and clearly distinguish this crankshaft from standard PX200 long-stroke crankshafts.

Equally important is the special clutch side: The gear teeth are specifically designed for the POLINI clutch hub 230.0506 and the HT clutch system. Anyone building the POLINI 244 should therefore plan the crankshaft, cylinder, and clutch as a unified system from the very beginning.

FAQ on the POLINI Racing Crankshaft 210.0095