POLINI SI Crankcase (manufacturer reference: 170.0210) ā a crankcase designed by POLINI, tailored for urban mopeds. This crankcase aims to optimize the intake gas flow with a reed valve that has increased timing compared to the original, which, depending on the engine configuration, can result in better efficiency and improved engine behavior at low and mid-range RPMs.
  - Compatibility: intended for use with original cylinders and oversized cylinders (pistons Ć 41, 43, and 46 mm).
- Versions: available in three versions depending on the type of moped (check the version suitable for your model).
- Crankshaft / clutch: the increased timing of the reed valve generally allows assembly without modification of the crankshaft. If you have a reinforced clutch (design A), installation remains possible: it will not alter the maximum power and will improve torque at low RPMs.
- Installation: requires removal of the engine block from the chassis, complete disassembly, and careful cleaning of all parts to be reused, including the new crankcases.
Product suitable for users looking for a replacement part or a base for engine preparation on classic urban models such as Piaggio Si / Grillo 50 cm3. Polini offers a robust part designed to optimize engine behavior without unverified technical promises.