Cylinder - POLINI 244cc Gray Cast Iron, Ø72mm, Stroke = 60mm, Connecting Rod Length = 127mm - Vespa PX200, Rally200 - with cylinder head

POLINI 244 cc – New Large-Frame Concept with a Bore of 72 mm and a 127-mm Connecting Rod

With the POLINI 244 cc cylinder kit 140.0241, POLINI is taking a significantly different design approach for Vespa 200 large-frame engines than with classic 210- or 221-cm³ cylinders. The combination of a 72 mm bore, 60 mm stroke, and an exceptionally long 127 mm connecting rod creates a high-displacement engine configuration in which a large portion of the transfer port system is located high up in the cylinder.

The cylinder is made of gray cast iron and is sold with a cylinder head. POLINI explicitly specifies the specially developed crankshaft 210.0095 with a 60 mm stroke and 127 mm connecting rod for this kit. This means the cylinder is not a universal 60-mm long-stroke kit for a standard PX200 crankshaft, but rather part of a coordinated overall design.

244 cm³ Cast iron Ø72 mm 60 mm stroke 127 mm connecting rod PX200 / Rally200 Housing modification required

Design principle: large cylinder, long connecting rod, high-mounted overflow ports

In classic Vespa PX cylinders, the cylinder base protrudes far into the engine case. The POLINI 244 design features a significantly different layout. The combination of a large 72-mm bore and a long 127-mm connecting rod creates more vertical clearance and allows the overflow channels to be positioned deep within the cylinder.

Accordingly, the product image does not show a classic cylinder base protruding far into the crankcase. However, this does not mean that the kit can be installed on an original engine housing without modification.

The POLINI manual does not describe boring out the housing to create a classic deep cylinder base. Instead, the necessary machining focuses on smoothly blending the overflow channels and transitions. However, according to the manufacturer, precisely these steps are mandatory for original housings.

POLINI engine cases must also be adapted

Even when using a POLINI engine housing, the manual requires adjustments to the overflow channels. Here, the base gasket is again used as a reference. The goal is to achieve as smooth a transition as possible between the housing, the gasket, and the cylinder, without steps or changes in cross-sectional area.

Light deburring of the cylinder windows is recommended

POLINI also recommends lightly rounding the edges of the windows in the cylinder bore before final assembly. This is intended to remove sharp edges and ensure smooth passage of the piston rings. The port geometry and valve timing must not be altered in the process.

Only with POLINI crankshaft 210.0095

To ensure the cylinder kit functions correctly, POLINI explicitly requires the 210.0095 crankshaft with a 60 mm stroke and a 127 mm connecting rod length. A standard PX200 long-stroke crankshaft with 110-mm connecting rods is therefore not a suitable alternative.

Special feature on the clutch side

The crankshaft 210.0095 included in the kit features a toothed section on the clutch side. POLINI specifies the special toothed clutch hub insert 230.0506 for this purpose, which allows the POLINI HT Clutch to be mounted.

A conventional PX clutch with a standard crankshaft mounting cannot therefore simply be used as-is. Other clutch solutions may only be used if their manufacturer explicitly confirms compatibility with this POLINI gear ring.

Alternative Crankshaft: BGM PRO BGM031128G

In addition to the 210.0095 crankshaft specified by POLINI, the BGM PRO crankshaft BGM031128G is also very well suited for the 244 configuration. It also has a 60 mm stroke but uses a 128 mm-long connecting rod, which is 1 mm longer than the POLINI crankshaft.

A major practical advantage lies on the clutch side: The BGM PRO crankshaft features a conventional PX crankshaft journal for the clutch mount. This means you are not limited to the special toothed POLINI hub 230.0506 or the POLINI HT Clutch. Instead, you can use standard compatible PX clutch systems with a conventional mounting.

128-mm connecting rod: Precisely adjust the valve timing angle using spacers

The 1 mm longer connecting rod of the BGM031128G does not change the stroke but shifts the geometric position of the piston relative to the cylinder. Using a suitable combination of foot spacers and, if necessary, head spacers, the cylinder can therefore be precisely positioned.

This allows the position of the intake and exhaust ports relative to the piston to be adjusted, thereby changing the valve timing angles within the mechanically feasible range according to the desired engine design. This provides additional flexibility for a design focused on high revs, torque, or power.

Squeeze Clearance and Compression Ratio

POLINI specifies a squish clearance of 1.4 to 1.6 mm and a compression ratio of 12:1 for the kit. The squish gap must be measured before final assembly. To do this, use 0.3- and 0.5-mm base gaskets as specified in the instructions and combine them as appropriate.

Break-in, Fuel, and Tuning

POLINI recommends a break-in period of at least 500 km, during which the engine should not be subjected to sustained heavy loads and should always be allowed to reach full operating temperature before being subjected to higher loads. For fuel, POLINI lists 98/100 octane E5 as the preferred choice and 95 octane E5 as the recommended minimum. The manufacturer expressly advises against using 95 E10.

After installation, the carburetor tuning and clutch setup must be adjusted to the specific engine being used. Especially with a 244-cm³ engine, the jet settings should not be carried over from a smaller setup.

Technical Data

Product image and visible components

The current POLINI product image shows, in addition to the cylinder and cylinder head, the piston, piston pins, retaining rings, gaskets and/or spacers, mounting hardware, and a separate exhaust manifold, among other components. The actual contents of the package are determined by the POLINI packaging or parts list accompanying the item.

Conclusion

The POLINI 244 is a standalone large-displacement design for the Vespa 200 engine. A 72-mm bore, 60-mm stroke, and a 127-mm connecting rod allow for a significantly different cylinder geometry than that of classic PX200 kits. The system is specifically designed to work with the 210.0095 crankshaft.

The key point for installation: Despite the unusual cylinder base design, the cylinder cannot be installed without modifying the engine casing. Both original and POLINI casings must be properly aligned in the area of the overflow port. If you perform this work carefully and properly adjust the compression edge, ignition, carburetor, and clutch, you’ll end up with a technically fascinating foundation for a very high-displacement Vespa large-frame engine.

FAQ on the POLINI 244 cc Cylinder