Wiseco WK1290 Complete Piston Kit Standard 84mm Bore Yamaha 760 2-Stroke PWC

The Wiseco WK1290 is a complete forged piston kit designed for the standard 84mm bore on Yamaha 760cc twin-cylinder two-stroke personal watercraft engines. This kit provides a direct OEM-replacement solution for engines in need of a top-end rebuild, delivering the strength and precision Wiseco is known for in the powersports industry.

Each WK1290 kit includes all the components needed for a complete piston installation: forged piston, piston rings, wrist pin, and circlips — everything required to return your engine to factory specification.

Key Features:

• High-Silicon Forged Aluminum Construction — Wiseco pistons are forged from high-silicon, low-expansion aluminum alloy, offering superior strength, reduced weight, improved heat transfer, and extended service life compared to cast alternatives
• Standard 84mm Bore — Designed as a standard-size replacement for Yamaha 760cc twin-cylinder PWC engines; oversize variants (WK1291–WK1294) available from 84.5mm up to 86mm for bored or worn cylinders
• CNC Diamond-Turned Finish — Computer-controlled turning centers deliver a precision finish with minimal size variation for reliable fitment in cast iron, chrome, Nikasil, and boron composite cylinder bores
• Complete Kit — Includes forged piston, dual piston rings, hardened wrist pin, and circlips for a full single-cylinder top-end replacement
• 2-Stroke Forged Series — Part of Wiseco's proven 2-stroke PWC piston line, engineered specifically for Yamaha 760cc marine applications

The WK1290 is the standard bore option in the Wiseco 760 series kit lineup, with corresponding individual piston part number 757M08400. Compatible cylinder sleeve part number is 3233FA for cylinders requiring resleeving to accept Wiseco oversizes.