ProX 28.SIS4338-2 Steel Intake Valve Conversion Set for Kawasaki KX250F

Latest addition to the ProX program is the Steel Intake and Exhaust Valve & Spring Kits. This kit is offered as an alternative where the OEM application uses Titanium valves. ProX has now developed the Steel Intake and Exhaust Valve & Spring Kits, containing a set of steel intake or exhaust valves plus a set of specially designed stronger valve springs. The ProX kit just replaces the OEM valves & valve springs and can be installed using the OEM retainers, bases and valve seals.

The ProX 28.SIS4338-2 Intake Valve Conversion Set provides a durable steel-valve alternative for Kawasaki KX250F applications originally equipped with titanium intake valves. Designed as a complete replacement solution, this kit includes steel intake valves and specially engineered stronger valve springs to support the added weight of steel components while maintaining dependable valvetrain performance.

Each valve features a nitrided surface that delivers high microhardness and a smooth finish to help reduce friction between the valve stem and guide. The valve springs are manufactured from premium chrome vanadium steel for improved strength, performance, and durability during high-RPM operation. This construction makes the kit well suited for demanding riding conditions and engine rebuilds where long-term valve-train reliability is important.

The ProX conversion set is designed for straightforward installation using the original equipment retainers, spring bases, and valve seals. No additional engine modifications are required, and the system remains fully rebuildable with compatible OEM components. Supplied as a complete package, the 28.SIS4338-2 kit offers an efficient replacement option for restoring intake valve performance on select Kawasaki motocross engines.

Fitment: 2009 Kawasaki KX250F and 2010 Kawasaki KX250F. Brand: ProX. Manufacturer part number: 28.SIS4338-2. Vendor part number: 28.SIS4338-2.

Features:

• Steel intake valves provide increased durability and reduced wear under extreme operating conditions
• Nitrided valve surfaces offer high microhardness and a smooth finish to reduce friction between the valve stem and guide
• Stronger valve springs are designed to accommodate the additional weight of steel valves
• Compatible with OEM retainers, spring bases, and valve seals without requiring additional engine modifications
• Premium chrome vanadium steel springs deliver improved performance and durability at high engine speeds
• Complete replacement package supports quick, efficient, and cost-effective installation
• Fits 2009 Kawasaki KX250F and 2010 Kawasaki KX250F

Fitment:
2009 Kawasaki KX250F
2010 Kawasaki KX250F