{"product_id":"keith-black-kb258-010-80-inch-evolution-flat-top-piston-kit-010-oversize","title":"Keith Black KB258.010 80-Inch Evolution Flat-Top Piston Kit .010 Oversize","description":"Keith Black flat top piston set is .010 oversize with an 8.6:1 compression ratio for 1984-up Big Twin Evolution models.\n\u003cp\u003eUpgrade your Harley-Davidson Evolution engine with the Keith Black KB258.010 80-Inch Evolution Flat-Top Piston Kit. Designed for an engine bore of 3.498 inches, this .010-inch oversize piston kit delivers an 8.5:1 compression ratio for improved power and fuel efficiency. The piston is manufactured from Keith Black hypereutectic alloy and cast in a permanent steel mold, producing a lightweight, durable component engineered for dependable performance in street and touring applications. This kit is intended for compatible 1984–1993 Harley-Davidson FXR models equipped with an 80-inch Evolution engine.\u003c\/p\u003e\u003cp\u003eThe hypereutectic alloy provides low heat transfer, helping keep the piston skirts cooler during operation and minimizing expansion. Reduced expansion supports consistent piston-to-cylinder clearance, while the lightweight construction helps reduce reciprocating mass. High ring placement improves combustion efficiency, increases top-ring operating temperature, and helps reduce detonation. Together, these design features support stronger engine performance, improved economy, and long-term durability when the piston is correctly fitted and installed.\u003c\/p\u003e\u003cp\u003eProper break-in is essential for new pistons and rings. Run the engine at moderate speeds for at least 500 miles and avoid excessive operation in lower gears during this period. Always verify bore condition, piston-to-wall clearance, ring end gap, compression ratio, and all installation specifications before assembly. Refer to the Keith Black Conversion Piston Guide and\u003cbr\u003e\nFitment\u003cbr\u003e\nHarley Davidson FLST  1986\u003cbr\u003e\nHarley Davidson FLST  1987\u003cbr\u003e\nHarley Davidson FLST  1988\u003cbr\u003e\nHarley Davidson FLST  1989\u003cbr\u003e\nHarley Davidson FLST  1990\u003cbr\u003e\nHarley Davidson FLST  1991\u003cbr\u003e\nHarley Davidson FLST  1992\u003cbr\u003e\nHarley Davidson FLST  1993\u003cbr\u003e\nHarley Davidson FLST  1994\u003cbr\u003e\nHarley Davidson FLST  1995\u003cbr\u003e\nHarley Davidson FLST  1996\u003cbr\u003e\nHarley Davidson FLST  1997\u003cbr\u003e\nHarley Davidson FLST  1998\u003cbr\u003e\nHarley Davidson FLT  1984\u003cbr\u003e\nHarley Davidson FLT  1985\u003cbr\u003e\nHarley Davidson FLT  1986\u003cbr\u003e\nHarley Davidson FLT  1987\u003cbr\u003e\nHarley Davidson FLT  1988\u003cbr\u003e\nHarley Davidson FLT  1989\u003cbr\u003e\nHarley Davidson FLT  1990\u003cbr\u003e\nHarley Davidson FLT  1991\u003cbr\u003e\nHarley Davidson FLT  1992\u003cbr\u003e\nHarley Davidson FLT  1993\u003cbr\u003e\nHarley Davidson FLT  1994\u003cbr\u003e\nHarley Davidson FLT  1995\u003cbr\u003e\nHarley Davidson FLT  1996\u003cbr\u003e\nHarley Davidson FLT  1997\u003cbr\u003e\nHarley Davidson FLT  1998\u003cbr\u003e\nHarley Davidson FXD  1991\u003cbr\u003e\nHarley Davidson FXD  1992\u003cbr\u003e\nHarley Davidson FXD  1993\u003cbr\u003e\nHarley Davidson FXD  1994\u003cbr\u003e\nHarley Davidson FXD  1995\u003cbr\u003e\nHarley Davidson FXD  1996\u003cbr\u003e\nHarley Davidson FXD  1997\u003cbr\u003e\nHarley Davidson FXD  1998\u003cbr\u003e\nHarley Davidson FXR  1984\u003cbr\u003e\nHarley Davidson FXR  1985\u003cbr\u003e\nHarley Davidson FXR  1986\u003cbr\u003e\nHarley Davidson FXR  1987\u003cbr\u003e\nHarley Davidson FXR  1988\u003cbr\u003e\nHarley Davidson FXR  1989\u003cbr\u003e\nHarley Davidson FXR  1990\u003cbr\u003e\nHarley Davidson FXR  1991\u003cbr\u003e\nHarley Davidson FXR  1992\u003cbr\u003e\nHarley Davidson FXR  1993\u003cbr\u003e\nHarley Davidson FXR  1994\u003cbr\u003e\nHarley Davidson FXST  1984\u003cbr\u003e\nHarley Davidson FXST  1985\u003cbr\u003e\nHarley Davidson FXST  1986\u003cbr\u003e\nHarley Davidson FXST  1987\u003cbr\u003e\nHarley Davidson FXST  1988\u003cbr\u003e\nHarley Davidson FXST  1989\u003cbr\u003e\nHarley Davidson FXST  1990\u003cbr\u003e\nHarley Davidson FXST  1991\u003cbr\u003e\nHarley Davidson FXST  1992\u003cbr\u003e\nHarley Davidson FXST  1993\u003cbr\u003e\nHarley Davidson FXST  1994\u003cbr\u003e\nHarley Davidson FXST  1995\u003cbr\u003e\nHarley Davidson FXST  1996\u003cbr\u003e\nHarley Davidson FXST  1997\u003cbr\u003e\nHarley Davidson FXST  1998\u003c\/p\u003e","brand":"Keith Black","offers":[{"title":"Default Title","offer_id":44850101452842,"sku":"11-2218","price":253.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0692\/2285\/8794\/files\/11-2218.jpg?v=1789449317","url":"https:\/\/atticusgoods.com\/products\/keith-black-kb258-010-80-inch-evolution-flat-top-piston-kit-010-oversize","provider":"Atticus Goods","version":"1.0","type":"link"}