Wiseco PK1205 49.5mm Pro-Lite Piston Kit for 2002-2006 Yamaha YZ85

The Wiseco PK1205 is a 49.5mm (805M) Pro-Lite forged piston kit designed for 2002–2006 Yamaha YZ85 two-stroke dirt bikes. Engineered to deliver maximum power and durability in demanding race conditions, this kit includes everything needed for a professional-grade top-end rebuild.

Key Features:

• Forged construction: Manufactured entirely in-house in the USA using proprietary forge tooling, ensuring tight quality control from raw material to finished part
• Pro-Lite design: Optimized strength-to-weight ratio reduces reciprocating mass for improved throttle response and high-RPM performance
• Condensed grain structure: Unlike brittle cast pistons, Wiseco forgings feature aligned grain structure that delivers superior resistance to impact, fatigue, and high-stress failure
• Skirt coating: Factory-applied skirt coating reduces friction and improves break-in characteristics
• 49.5mm bore diameter: Standard bore size for OEM or light-hone rebuilds; compatible with stock cylinder dimensions
• Includes top-end gasket kit: Complete kit provides all necessary gaskets for a full top-end rebuild
• 2-stroke specific engineering: Developed and dyno-tested for two-stroke motorcycle applications to meet the power and heat demands of competitive motocross racing

Wiseco's vertically integrated manufacturing process — from forging to dyno validation — ensures every PK1205 piston meets the same exacting standards used by professional motocross racers. A direct upgrade over OEM cast pistons for the Yamaha YZ85.