ProX cast piston kit, designed for the Motorcycle Piston category. The piston designs are generally similar to OEM/stock configurations, with adjustments made by ProX engineers to improve performance. ProX cast pistons are very stable and manufactured through gravity casting using an aluminum alloy with approximately 18 percent silicon content. The silicon reduces thermal expansion, ensuring lasting performance. ProX two-stroke pistons are made for both cast iron cylinder linings and Nikasil cylinder liners. ProX offers a variety of oversized Nikasil cylinder liners, categorized into sizes A/B/C/D, with each increasing the diameter by 0.01 millimeters.