Honda 400EX/400X Wiseco 87mm 416 Big Bore Piston Kit & Athena/Cometic Top End Gasket Set

Ready to wake up your Honda 400EX or 400X?

This is a complete top end kit featuring a Wiseco 87mm piston (gives you that 416 big bore displacement), plus Athena and Cometic gaskets.

The piston is aluminum alloy, comes with rings and a wrist pin (20mm pin diameter), and is built for 4-stroke ATV engines.

The gasket set is top quality—Athena and Cometic are trusted names.

This kit bumps your displacement up for more torque and power, whether you're trail riding or racing.

All parts are new in the package, made in the USA, and come with a 1-year warranty.

The piston diameter is 87mm, so you'll need to bore your cylinder to match if it's not already.

OE part number 13101-KCY-670 is superseded by this kit.

California Prop 65 warning applies, but hey, performance parts always have that.