Wiseco 40058M07100 Forged Piston Kit Bore Compression - 458cc 71.00mm 10 1

The Wiseco 40058M07100 is a high-performance forged piston kit designed for 458cc twin-cylinder engines. This kit is a 1.00mm oversize piston bored to 71.00mm (standard bore: 70.00mm) with a 10:1 compression ratio and a dome volume of +19cc, making it ideal for performance rebuilds and AHRMA competition applications.

Wiseco forges this piston from high-silicon aluminum alloy, delivering an optimized strength-to-weight ratio with improved tensile strength for extended service life. The dedicated forging design and precision piston skirt geometry are engineered to maximize horsepower and torque output from the engine.

Kit Contents:

• 1 forged aluminum piston (71.00mm bore)
• 1 ring set (part# 2795XC)
• 1 wrist pin — 17mm unchromed (part# S523)
• 1 pair round wire pin locks / circlips — 17mm (part# CW17)

Key Specifications:

• Bore Size: 71.00mm (1.00mm / .040" oversize)
• Standard Bore: 70.00mm
• Stroke: 57.80mm
• Displacement: 458cc
• Compression Ratio: 10:1
• Dome Volume: +19cc
• Number of Cylinders: 2 (sold as individual piston kit — one piston per kit)
• Wrist Pin Diameter: 17mm

Important Installation Note: As an oversize piston, installation requires professional cylinder boring or re-sleeving to the specified 71.00mm diameter. This engine is a twin-cylinder design — two kits are required for a complete engine rebuild.

Wiseco has been manufacturing industry-leading forged pistons for over 75 years and supplies top racing teams competing in Supercross, Motocross, Moto GP, Superbike, and more. All Wiseco powersports piston kits are proudly made in the USA.