Keith Black flat top piston set with an 8.6:1 compression ratio .005-.040

Keith Black flat top piston set with an 8.6:1 compression ratio for 1984-up Big Twin Evolution models.

The Keith Black 390 hypereutectic alloy is cast in a permanent steel mold which makes it possible to build a light weight piston that makes more power and uses less fuel and lasts longer. Pistons are .005 over sized for a 3.498" bore and has a 8.5:1 compression ratio. The low heat transfer of the alloy keeps the skirts cool so piston expansion is minimal. The combination of a low heat transfer piston alloy and high compression ring placement increases power and economy. The high ring placement alone reduces detonation and increases the top ring teperature. **Note: Run engine at moderate speeds for at least 500 miles, avoiding excessive running in lower gears, in order to properly break-in new pistons and rings.

Vt-11-2217

Vt-11-2218

Vt-11-2219

Vt-11-2220

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More Information

FXST 1984-1998

FLT 1984-1998

FXD 1991-1998

FXR 1984-1994

FLST 1986-1998