Wiseco PK1343 GP Series 2-Stroke Top End Piston Kit 52.50mm Bore YZ85 Supermini

The Wiseco PK1343 is a GP Series forged 2-stroke top end piston kit designed for the Yamaha YZ85 with a 52.50mm bore (767M), purpose-built for Supermini racing applications requiring cylinder sleeving or replating to a ceramic composite bore. With a stroke of 47.8mm and a resulting displacement of approximately 103cc, this kit delivers the power and durability demanded by competitive Supermini racers.

The GP Series builds on Wiseco's proven Pro-Lite foundation, adding a suite of advanced protective coatings and finish treatments designed for endurance and sustained high-RPM 2-stroke performance. Every piston is engineered, forged, and machined in the USA at Wiseco's facility in Mentor, OH, using aerospace-grade alloy for an optimal strength-to-weight ratio.

Key Features:

• GP Series Forged Construction — Dedicated forging using aerospace alloy delivers a superior strength-to-weight ratio over cast alternatives
• Electra-Coated Crown, Ring Groove & Pin Bore — Resists wear, combustion heat damage, and ring micro-welding for extended service life
• ArmorGlide Skirt Coating — Reduces piston-to-wall friction to optimize power output and performance potential
• CNC Machined — Optimized cam shape profile engineered for peak horsepower and maximum service life
• Single-Ring 2-Stroke Design — Reduces reciprocating weight and friction for improved throttle response
• 52.50mm Bore / 103cc Displacement — Standard Supermini big bore size; cylinder sleeving or replating to ceramic composite bore required
• Complete Top End Kit — Includes piston, ring set, wrist pin, circlips, top-end wrist pin bearing, and top-end gasket kit

Kit Contents:

• 1x Forged GP Series Piston (52.50mm)
• 1x High-performance ring set
• 1x Wrist pin
• 2x Circlips
• Top-end wrist pin bearing
• Complete top-end gasket kit

Important Note: This kit requires cylinder sleeving or replating to a ceramic composite bore. It will not fit a stock 85cc cylinder unless it has been properly bored to accept the 52.50mm piston.

Wiseco's PK1343 is the trusted choice of top race teams across Supercross, Motocross, and Supermini competition, delivering race-proven reliability and power for serious riders.