Polini has recently added upgrades for the Yamaha Minarelli engine to its collection of parts. These upgrades aim to increase power and enhance the durability of the engine’s internals. Designed specifically for Yamaha motors, Polini’s parts allow the small engine to achieve higher power output. The upgrades include a selection of crankshafts and cylinder kits.

Starting with the crankshafts, the Minarelli engines found on CY, MY, and CW models from Yamaha can benefit from improved durability and resistance with this kit. The connecting rod is machined and compatible with a 12mm piston, providing an alternative to the original 10mm piston pin. This upgrade complements the cylinder kit, which offers 40 or 70cc cast-iron cylinder options. The Minarelli engine, whether in a horizontal or vertical configuration, has two available part numbers for these upgrades.

Polini For Race Ø 12 Crankshafts for Yamaha Minarelli:

• 210.0048/12 – Yamaha Horizontal
• 210.0049/12 – Yamaha Vertical

The next set of upgrades includes various cylinder kits that consist of the head, piston, piston rings, pin, and gaskets. These kits work in conjunction with the crankshaft to maximize compatibility and power gains over the stock setup. Polini’s cylinder kits offer improved reliability during extended periods of stress, thanks to the special alloys used in their construction. These alloys also provide resistance to high temperatures.

The cylinder head is made of durable cast iron, while the skirt features a special alloy with a high siliceous content for enhanced temperature resistance and performance. The piston rings included in the kit are made of spheroidal cast iron, a wear-resistant material that has been rebored and lapped according to Polini’s product page.

The piston itself is crafted from a special aluminum alloy that offers a high coefficient of heat exchange. The combustion chamber has been redesigned to accommodate high compression ratios and is designed with high turbulence in mind.

It is important to note that the cylinder kit requires the crankshaft kit, as they are intended to be used together. Make sure to order both at the same time to ensure compatibility.

Polini cylinder kits for Yamaha Minarelli engines Ø 12:

• 166.0074/12
• 166.0076/12
• 166.0083/12

Both kits are made in Italy and are reasonably priced. The crankshaft kit costs 139 EUR plus VAT, while the cylinder kit is priced at 150 EUR plus VAT. In US Dollars, this translates to around $150 for the crankshaft and approximately $160 for the cylinder kit, excluding VAT.