Polini Evolution iron cylinder kit Minarelli Vertical b.12mm

Polini cylinder kit Evolution iron 70cc 12mm pin for Minarelli Vertical.

The Polini Evolution iron 70cc cylinder kit for vertical Minarelli engines (MBK Booster, Yamaha, etc.) is designed for those seeking a true leap in performance. This version with a 12 mm pin is based on a very solid technical foundation, optimized for competition or demanding sport use.

Although it is a cast iron cylinder, nothing in this kit is conventional. Polini has completely redesigned the thermal group, applying solutions that are usually only seen in high-end engines. The result: more power, more torque, and better response throughout the entire rev range.

Among the key innovations is the integrated reeds box in the cylinder with two exclusive channels that feed the transfers directly, improving engine charge and low RPM thrust. In addition, the kit includes a 4-petal reeds box, much more effective than the traditional 2-petal ones, and a 360° manifold compatible with Polini CP carburettors from 17 to 24 mm. This allows you to fit the filter you prefer without space or orientation issues.

With the recommended configuration, this kit can deliver up to 14 real HP, a figure well above what is usual in iron kits. The torque curve is constant and full, perfect both for acceleration and for maintaining speed on straights.

Technical specifications:

• Stroke: 39.2 mm
• Connecting rod: 80 mm
• Cylinder diameter: 47 mm
• Recommended squish: 1 ± 0.1 mm
• Ignition timing: Original
• Recommended Spark plug: NGK heat grade 9
• Suggested carburettor setup:
• Polini CP 24 carburettor
• Open cone-type air filter
• Main jet: 113
• Pilot jet: 38
• Slide: Ø25/30
• Needle: 14/22 in 2nd groove
• Atomizer: 2.7
• Float: 5 g

Recommended parts

• Polini CP carburettor from 19 to 24 mm (ideally the 24 with open cone-type filter)
• Polini For Race 4 or Scooter Team exhaust
• High-Speed transmission or sports variator