Keith Black KB258.040 80-Inch Evolution Flat Piston Kit .040 Oversize

Keith Black flat top piston set is .040 oversize with an 8.6:1 compression ratio for 1984-up Big Twin Evolution models.

The Keith Black KB258.040 80-inch Evolution Flat Piston Kit is designed with a .040-inch oversize for a 3.498-inch bore and an 8.5:1 compression ratio. The hypereutectic alloy is cast in a permanent steel mold to support a lightweight piston design intended to provide increased power, improved fuel economy, and extended service life.

The alloy's low heat transfer helps keep the piston skirts cooler, minimizing expansion. Combined with high compression ring placement, this design supports power and economy while helping reduce detonation and increase top ring temperature. The kit fits 1984 through 1993 Harley-Davidson FXR models as specified in the product data.

For proper break-in, run the engine at moderate speeds for at least 500 miles and avoid excessive operation in lower gears. Keith Black KB258.040 is supplied as a set. A compatible suggested item is the 11-1367 80-inch Shovelhead Piston Ring Set .040.

Features:

• Brand: Keith Black
• Part Number: KB258.040
• Application: 80-inch Evolution flat piston kit
• Oversize: .040-inch oversize
• Bore: Designed for a 3.498-inch bore
• Compression Ratio: 8.5:1
• Material: Hypereutectic alloy
• Design: Permanent steel mold casting with low heat transfer
• Ring Placement: High compression ring placement
• Quantity: Supplied as a set
• Fitment: 1984–1993 Harley-Davidson FXR models
• Break-In: Run at moderate speeds for at least 500 miles and avoid excessive operation in lower gears
• Accessory Items: 16-0622 - Ring-O-Matic Ring Compressor Tool Kit, 60-0167, 16-0075 - Wrist Pin Ring Tool

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