Keith Black KB258.005 80-Inch Evolution Flat Piston Set, .005 Oversize

Keith Black flat top piston set is .005 oversize with an 8.6:1 compression ratio for 1984-up Big Twin Evolution models.

The Keith Black KB258.005 80-inch Evolution flat piston set features a hypereutectic alloy cast in a permanent steel mold. This construction supports a lightweight piston design intended to help make more power, use less fuel, and provide extended service life. The pistons are .005 inch oversize for a 3.498-inch bore and have an 8.5:1 compression ratio.

The alloy's low heat transfer helps keep the skirts cooler, minimizing piston expansion. Combined with high compression ring placement, this design is intended to improve power and economy. High ring placement also helps reduce detonation and increase top ring temperature. The set is listed for 1984–1993 Harley-Davidson FXR applications.

Keith Black recommends running the engine at moderate speeds for at least 500 miles while avoiding excessive operation in lower gears to properly break in new pistons and rings. Refer to the manufacturer's fitment and installation guide before installation. This product is supplied as a set and is made in the USA.

Brand: Keith Black. Part number: KB258.005.

Features:

• Construction: Hypereutectic alloy pistons cast in a permanent steel mold
• Bore Size: .005 inch oversize for a 3.498-inch bore
• Compression Ratio: 8.5:1
• Design: Low heat transfer alloy helps minimize piston expansion
• Ring Placement: High compression ring placement is intended to improve power and economy
• Application: Fits 1984–1993 Harley-Davidson FXR models
• Unit of Measure: Set
• Country of Origin: USA

Fitment:
Harley Davidson FLST 1986
Harley Davidson FLST 1987
Harley Davidson FLST 1988
Harley Davidson FLST 1989
Harley Davidson FLST 1990
Harley Davidson FLST 1991
Harley Davidson FLST 1992
Harley Davidson FLST 1993
Harley Davidson FLST 1994
Harley Davidson FLST 1995
Harley Davidson FLST 1996
Harley Davidson FLST 1997
Harley Davidson FLST 1998
Harley Davidson FLT 1984
Harley Davidson FLT 1985
Harley Davidson FLT 1986
Harley Davidson FLT 1987
Harley Davidson FLT 1988
Harley Davidson FLT 1989
Harley Davidson FLT 1990
Harley Davidson FLT 1991
Harley Davidson FLT 1992
Harley Davidson FLT 1993
Harley Davidson FLT 1994
Harley Davidson FLT 1995
Harley Davidson FLT 1996
Harley Davidson FLT 1997
Harley Davidson FLT 1998
Harley Davidson FXD 1991
Harley Davidson FXD 1992
Harley Davidson FXD 1993
Harley Davidson FXD 1994
Harley Davidson FXD 1995
Harley Davidson FXD 1996
Harley Davidson FXD 1997
Harley Davidson FXD 1998
Harley Davidson FXR 1984
Harley Davidson FXR 1985
Harley Davidson FXR 1986
Harley Davidson FXR 1987
Harley Davidson FXR 1988
Harley Davidson FXR 1989
Harley Davidson FXR 1990
Harley Davidson FXR 1991
Harley Davidson FXR 1992
Harley Davidson FXR 1993
Harley Davidson FXR 1994
Harley Davidson FXST 1984
Harley Davidson FXST 1985
Harley Davidson FXST 1986
Harley Davidson FXST 1987
Harley Davidson FXST 1988
Harley Davidson FXST 1989
Harley Davidson FXST 1990
Harley Davidson FXST 1991
Harley Davidson FXST 1992
Harley Davidson FXST 1993
Harley Davidson FXST 1994
Harley Davidson FXST 1995
Harley Davidson FXST 1996
Harley Davidson FXST 1997
Harley Davidson FXST 1998