Kawasaki KLX400 Piston Sets - Wiseco - 90.00 mm Bore, 13.5:1 CR - '03-'06. This Wiseco forged piston kit is made for 2003–2006 KLX/KFX400 engines and provides a direct-fit rebuild option for riders and tuners seeking durable, application-specific components.

Wiseco's 4-stroke pistons are engineered and machined in the USA (Mentor, OH) to meet the tolerances required for powersports engines. These pistons use dedicated forgings to balance strength and weight, improving tensile strength compared with many cast designs. The kit includes the piston(s) plus high-quality rings, wrist pin(s), and circlips for a complete replacement. Suited for performance rebuilds or maintenance, this kit supports a 90.00 mm bore and a 13.5:1 compression ratio specified for the listed model years.

Features

• Fitment: Kawasaki KLX/KFX400, model years 2003–2006
• Bore and ratio: 90.00 mm bore, 13.5:1 compression ratio
• Complete kit: piston(s), rings, wrist pin(s), circlips included
• Forged and machined in the USA (Mentor, OH) to tight tolerances
• Improved tensile strength and optimized strength-to-weight from dedicated forgings

If you have questions or want help confirming fitment, call us directly — we’re happy to assist. We offer installation and customization services at our two locations in Austin, Texas and the Los Angeles, California area. Call 512-982-9393 (TX) or 562-981-6800 (CA) for parts, service, or to schedule work. If you are considering purchasing multiple items, please contact us for possible shipping discounts. We install on premises at both locations.

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