KPMI Black Diamond Exhaust Valve - HD Evolution 1987-1999 — Harley-Davidson (1984-1999)

KPMI Black Diamond exhaust valve for Harley Evolution engines, precision-forged from stainless steel and treated with a proprietary German impregnation process that hardens the surface to .002" depth. Delivers superior wear resistance and corrosion protection compared to chrome or nickel plating, with reduced friction for longer valve life.

Features

• Stainless steel one-piece forging
• German Black Diamond® impregnation process
• Improved wear resistance and corrosion protection
• Excellent flow characteristics
• Lightweight construction

Specifications

• Brand: KPMI
• Manufacturer Part #: 20-4170
• Length: 3.55 in
• Width: 4.7 in
• Height: 1.55 in
• Weight: 0.19 lbs

Fitment

Fits Harley-Davidson Evolution engines, 1987-1999 model years.

Frequently Asked Questions

Is this an intake or exhaust valve?

This is an exhaust valve. KPMI makes separate part numbers for intake valves.

What makes Black Diamond® different from standard stainless valves?

The German impregnation process hardens the surface to .002" depth, reducing friction and improving wear resistance beyond standard chrome or nickel plating.

Will this fit my 2000+ Twin Cam engine?

No — this valve is for Evolution engines only (1987-1999). Twin Cam models require different valve part numbers.

Do I need new valve seats when I install these?

Check your cylinder head condition. If seats are pitted or worn, have them resurfaced or replaced by a machine shop during your engine rebuild.