549M07750 Wiseco .060 Piston Kit for Kawasaki JS300 300SX 1986-1991 77.50 mm

Wiseco .060 Piston Kit for Kawasaki JS300/300SX

This Wiseco .060 overbore piston kit for Kawasaki JS300 and 300SX models brings the bore to 77.50 mm, with OEM cross-reference 549M07750, to rebuild a worn two-stroke top end.

Overview

This Wiseco .060 piston kit for Kawasaki JS300 and 300SX jet skis is built for riders who need a larger overbore to save a damaged cylinder. The 77.50 mm bore takes the cylinder out to its practical limit, making it a common choice on high-hour engines that have already been rebuilt. It serves owners restoring or servicing 1986-1991 JS300 and 300SX models with a reliable forged piston kit for Kawasaki applications.

Built For Performance

• Forged piston construction for durability in two-stroke service
• .060 in / 77.50 mm overbore size for heavily worn bores
• Kit includes piston, rings, wrist pin, and circlips
• Cross-references Wiseco 549M07750 for straightforward lookup
• Made for the 300 cc Kawasaki stand-up engine family

Fits These Machines

• for Kawasaki JS300, 1986-1991
• for Kawasaki JS300SX, 1986-1991

On-The-Job Use

• Full top end rebuild on a tired 300 cc stand-up jet ski
• Boring out a scored or pitted cylinder to a clean bore
• Restoration projects where original pistons are no longer available

Specs At A Glance

Good To Know

Q: Can I run this piston in a standard bore cylinder? A: No, the .060 overbore requires the cylinder to be bored and honed to 77.50 mm first. Confirm with a machinist that the cylinder wall has enough material left.

Q: Is this an original Kawasaki part? A: No, this is a Wiseco piston kit made for Kawasaki JS300 and 300SX applications. It is an aftermarket replacement rather than an OEM Kawasaki piston.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.