Wiseco 819M04020 2-Stroke Forged Piston Kit 40.20mm Bore Polini Works 50

The Wiseco 819M04020 is a complete 2-stroke forged piston kit featuring a 40.20mm standard bore, designed specifically for the Polini Works 50. Engineered and machined in the USA at Wiseco's facility in Mentor, OH, this piston kit reflects over 80 years of 2-stroke piston manufacturing expertise dating back to 1941.

Key Features:

• Forged High-Silicon Aluminum Construction: Forged from high-silicon, low-expansion aluminum alloy for superior tensile strength, reduced weight, improved heat transfer, and extended service life compared to cast alternatives.
• CNC Diamond-Turned Finish: Each piston is precision-machined on CNC computer-controlled turning centers, delivering a consistent, accurate finish with no size variation across cylinder bore compositions including cast iron, chrome, Nikasil, and boron composite.
• Dedicated Forging Design: Designed and built specifically for 2-stroke powersports engines, with optimized strength-to-weight ratio achieved through dedicated forgings and targeted lightening operations.
• Oversize Availability: Wiseco's broad range of oversize pistons helps extend the service life of cast iron-lined cylinders. Chrome, Nikasil, and boron composite cylinders can be resleeved to accommodate Wiseco oversizes.
• Complete Kit: Includes the forged piston, high-quality piston ring(s), wrist pin, and circlips — everything needed for installation.

Built for both competitive racers and recreational riders, the Wiseco 819M04020 piston kit delivers the performance and reliability that Wiseco has been known for across decades of powersports engine development.