Wiseco PK1358 Forged Piston Kit with Top-End Gaskets - 97mm 12.5 1 for YZ/WR450F

The Wiseco PK1358 is a complete forged piston kit designed for the 2003–2005 Yamaha YZ450F and WR450F. Featuring a 97.00mm bore (Forge Code 4785M) and a high-compression 12.5:1 compression ratio, this kit delivers the performance and durability demanded by serious off-road and motocross riders. The kit includes the forged piston, high-performance piston rings, alloy wrist pin, circlips, and a top-end gasket kit—everything needed for a complete top-end rebuild.

Forged in the USA for Maximum Strength:

Wiseco pistons are engineered, forged, and machined at their facility in Mentor, Ohio. Unlike cast pistons, Wiseco's forged construction produces a condensed, aligned grain structure that delivers significantly higher mechanical strength, superior impact resistance, and improved fatigue life. This makes them the preferred choice for high-performance and racing applications where reliability under extreme conditions is non-negotiable.

Key Features:

• 97.00mm bore diameter — Forge Code 4785M
• 12.5:1 compression ratio for increased power output
• ArmorGlide skirt coating reduces friction, minimizes piston rock noise, and promotes a tighter bore fit for improved ring seal
• Dedicated forging designed specifically for this engine application — optimized strength-to-weight ratio using aerospace-grade alloy
• Includes: forged piston, high-performance ring set, alloy wrist pin, circlips, and top-end gasket kit
• Engineered and manufactured entirely in the USA
• Built to tighter tolerances than OEM for superior performance and service life

Whether you're rebuilding for the track or the trail, the Wiseco PK1358 piston kit provides the foundation for a reliable, high-output top-end that withstands the rigors of competitive riding. Always inspect and measure your cylinder bore before installation.