Wiseco WK1103 Kawasaki 900 ZXI STX STS Pro-Lite 2-Stroke Forged Piston Kit 74.5mm Overbore

The Wiseco WK1103 is a Pro-Lite Series 2-stroke forged piston kit designed for Kawasaki 900 personal watercraft engines. Featuring a 74.50mm (+1.5mm overbore) bore diameter and displacing a big-bore 928cc, this kit delivers the strength, durability, and lightweight performance demanded by PWC enthusiasts and competitive riders alike. Engineered, forged, and machined in the USA, this kit is an ideal solution for top-end engine rebuilds on Kawasaki 900 ZXI, STX, and STS models.

Key Features:

• Forged aerospace-grade aluminum construction — the forging process compresses molecular density and aligns grain flow for superior resistance to impact, fatigue, and heat versus cast alternatives
• Pro-Lite extra lightweight design — dedicated lightening operations reduce reciprocating mass for instant throttle response
• CNC-machined piston skirt profile — computer-engineered cam shape minimizes cylinder wall friction for peak power and extended service life
• Horizontal slot-pin oiling — reduces friction and provides scuff resistance along with a pressure seal groove for maximum ring seal
• Anti-detonation grooves and precision ring land diameter — eliminate ring blow-by while maximizing performance and sealing integrity
• Compatible with all cylinder bore compositions — cast iron, chrome, Nikasil, and boron composite cylinders
• 74.50mm bore / +1.5mm oversize — extends cylinder life and restores compression on worn bores

Kit Includes:

• Forged piston — Part #659M07450
• Ring set — Part #2933TD
• Wrist pin — Part #S512
• Circlip — Part #CW20
• Top-end gasket set — Part #W5459

Built on over 80 years of motorsports engineering heritage, Wiseco's state-of-the-art facility in Mentor, Ohio combines 3D design techniques and finite element modeling to ensure every piston delivers the highest strength-to-weight ratio for its specific application. The WK1103 is the trusted choice for rebuilding Kawasaki 900 PWC engines with confidence.