Wiseco PK1603 Pro-Lite 2-Stroke Piston Top End Kit 54mm for KX125 2004-2008

The Wiseco PK1603 Pro-Lite Top End Kit is a complete 54.00mm (standard bore) forged piston kit engineered specifically for the 2004–2008 Kawasaki KX125. Designed, forged, and machined in the USA at Wiseco's Mentor, OH facility, the Pro-Lite is the forged 2-stroke piston that built Wiseco's reputation — combining decades of racing heritage with modern manufacturing precision.

About the Pro-Lite Piston:

• Forged from aerospace-grade aluminum alloy for a superior strength-to-weight ratio
• Dedicated forging geometry engineered for maximum heat transfer and throttle response
• CNC-machined with optimized cam shape and profile for peak horsepower and service life
• Lightweight construction delivers instant throttle response and maximum torque
• Race-proven design chosen by top competitive teams across all forms of motorsport
• High-performance ring set for extended service life and sustained power output
• High-quality alloy wrist pin (15 x 41mm, non-chromed) for consistent durability

Kit Contents (PK1603):

• Forged piston (834M05400) — 54.00mm standard bore
• Ring set (2126CS) — 54.00mm
• Wrist pin (S467) — 15 x 41mm, non-chromed
• Top end wrist pin bearing (B1013) — 15 x 19 x 19.5mm
• Top end gasket kit (W6253) — Kawasaki KX125 2003–2008

Key Specifications:

• Bore Size: 54.00mm (Standard)
• Stroke: 54.5mm
• Displacement: 125cc
• Piston Pin Diameter: 15mm
• Engine Type: 2-Stroke, Single Cylinder
• Wiseco Piston SKU: 834M05400

Compared to cast alternatives, Wiseco's forged pistons offer a condensed, aligned grain structure that produces higher mechanical properties and superior resistance to impact and fatigue — critical advantages under the high heat and sustained RPM demands of 2-stroke motocross competition. The PK1603 kit provides everything needed for a complete top end rebuild in one convenient package.