Keith Black 80 Inch Evolution Flat Piston Set.005 Oversize for Harley FXR (1984–1993)
Keith Black's Evolution flat-top pistons in.005 oversize are engineered for Harley-Davidson FXR models from 1984 to 1993, delivering a 3.498 in bore with an 8.5:1 compression ratio. The KB258.005 80 Inch Evolution Flat Piston Set is crafted from hypereutectic alloy and cast in a permanent steel mold to ensure precision, durability, and consistent performance.
The design features a.005 inch oversize to precisely fit a 3.498 inch bore, providing a reliable upgrade that can improve engine power and efficiency. The low heat transfer alloy helps keep piston skirts cooler, reducing expansion and wear over time. High ring placement together with the alloy properties enhances power output while helping resist detonation, contributing to better top-end temperature management and long-term engine reliability.
- Material: Hypereutectic alloy
- Casting: Permanent steel mold
- Oversize:.005 inch
- Bore: 3.498 in
- Compression Ratio: 8.5:1
- Heat Transfer: Low
- Design: High ring placement
- Break-in Instructions: Run engine at moderate speeds for at least 500 miles
- Country of Origin: USA
- Fitment: Harley Davidson FXR 1984–1993
- Part Number: KB258.005
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 is engineered for optimal performance in Harley Davidson FXR models from 1984 to 1993. Crafted from hypereutectic alloy, these pistons are cast in a permanent steel mold, ensuring durability and precision. The design features a.005 inch oversize to fit a 3.498 inch bore, providing a reliable upgrade that enhances engine power and efficiency. The pistons have an 8.5:1 compression ratio, balancing performance and fuel economy effectively. The low heat transfer alloy helps keep the piston skirts cool, minimizing expansion and reducing wear over time. High compression ring placement and the alloy's properties work together to boost engine power while decreasing detonation, leading to improved top-end temperature management and overall engine longevity.
Features:
- Material: Hypereutectic alloy for durability and heat resistance
- Casting: Permanent steel mold for precision and consistency
- Oversize:.005 inch for a perfect fit in a 3.498 inch bore
- Compression Ratio: 8.5:1 for balanced power and fuel efficiency
- Heat Transfer: Low heat transfer alloy reduces piston skirt temperature
- Design: High ring placement enhances power output and detonation resistance
- Break-in Instructions: Run engine at moderate speeds for at least 500 miles to ensure proper piston and ring seating
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
