ProX Steel Intake Valve and Spring Conversion Kit 28.SIS4409-1 for Kawasaki KX450F

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 Steel Intake Valve and Spring Conversion Kit, manufacturer part number 28.SIS4409-1 and vendor part number 19-9515-1, provides a durable replacement for OEM titanium intake valves and valve springs. Designed for Kawasaki KX450F motocross motorcycles from 2009 through 2018, this complete kit helps restore dependable valve-train performance under demanding riding and high-RPM conditions.

The kit includes steel intake valves and specially developed stronger valve springs engineered to accommodate the additional weight of steel valves. Nitrided valve surfaces provide increased microhardness and a smooth finish that helps 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 extended engine operation.

Installation is designed to use the original equipment retainers, spring bases, and valve seals, allowing the conversion to be completed without additional engine modifications. The ProX kit offers a practical, fully rebuildable solution for replacing worn or damaged OEM titanium intake components while supporting consistent engine operation.

Fitment: 2009-2018 Kawasaki KX450F.

Features:

• Steel intake valves increase durability and reduce wear in extreme operating conditions
• Nitrided valve surfaces provide high microhardness and a smooth finish for reduced stem-to-guide friction
• Specially designed stronger valve springs accommodate the added weight of steel valves
• Compatible with OEM retainers, spring bases, and valve seals for installation without further engine modifications
• Premium chrome vanadium steel springs support high-RPM performance and long-term durability
• Complete conversion package for efficient valve and spring replacement
• Size: Complete intake valve and spring conversion set
• Model: Intake Valve Conversion Set Ti Steel Kaw
• Brand: ProX
• Manufacturer part number: 28.SIS4409-1
• Vendor part number: 19-9515-1

Fitment:
2009 Kawasaki KX450F
2010 Kawasaki KX450F
2011 Kawasaki KX450F
2012 Kawasaki KX450F
2013 Kawasaki KX450F
2014 Kawasaki KX450F
2015 Kawasaki KX450F
2016 Kawasaki KX450F
2017 Kawasaki KX450F
2018 Kawasaki KX450F