KPMI 80-81900 Top End Service Kit – SS Valve Conversion w/ Springs – Yamaha YZ450F 2003-2005 / WR450F 2003-2006

Double valve life. Stock compression. Bulletproof 450.
The KPMI 80-81900 is a complete stainless steel top-end conversion kit for 2003–2005 YZ450F and 2003–2006 WR450F. Replaces fragile titanium valves with Black Diamond™ stainless, maintains stock compression via domed piston, and includes high-lift spring kit. We price-match reputable online stores—contact us to ensure you get the best deal!

What’s Included

• 2618 Alloy CNC Piston (domed, skirt-coated, stock compression)

• Piston Rings, Wrist Pin, Circlips

• KPMI Black Diamond™ S.S. Valves (intake + exhaust, stock head dia.)

• Dual Spring Titanium Retainer Kit (supports 0.440" lift)

• Cometic Top End Gasket Kit (head, base, seals)

• All seals, o-rings, and hardware

• Ready-to-install — no missing pieces

Key Features

• Black Diamond™ stainless valves — 2X life vs. OEM titanium

• Domed piston design — offsets valve dish, keeps stock CR

• Lightweight racing springs — supports aggressive cams & high RPM

• Fully CNC machined 2618 alloy — maximum strength, minimum weight

• Warning: Cancer and Reproductive Harm - www.P65Warnings.ca.gov

Fitment

• Yamaha YZ450F

  • 2003

  • 2004

  • 2005

• Yamaha WR450F

  • 2003

  • 2004

  • 2005

  • 2006

• Note: Verify cam lift ≤ 0.440" before install.

$736.95

SKU: 191-44032K / 80-81900
Weight: 1.80 lbs
Package: 8.00" × 8.00" × 2.37"
Same-day shipping if ordered by 3 PM EST

Installation Tips

1. Deglaze cylinder — 400-grit crosshatch

2. Torque head — follow Yamaha sequence (22 ft-lbs final)

3. Set valve lash — 0.004" in / 0.008" ex (cold)

4. Break in gently — 3 heat cycles, vary RPM