{"product_id":"keith-black-pistons-flat-top-pistons-kb258-020-for-big-twin-1984-1999","title":"Keith Black Pistons Flat Top Pistons KB258.020 for Big Twin 1984-1999","description":"\u003cp style=\"margin:1em 0\"\u003eThese Keith Black hypereutectic flat top pistons are engineered for Big Twin Evolution engines, featuring a cast 16% silicon alloy that delivers low thermal expansion for tighter piston-to-cylinder clearance. Designed specifically for air-cooled applications, they provide an 8.6:1 compression ratio with standard 80cc combustion chambers to ensure dependable, efficient power.\u003c\/p\u003e\u003cp style=\"margin:1em 0\"\u003eSupplied as a comprehensive engine set, each kit includes pistons, matching rings, wrist pins, and spiral locks. These components serve as direct performance replacements for OEM # 21943-83, ensuring a precise fit and reliable service life for your rebuild.\u003c\/p\u003e\n\u003ch3 style=\"margin:1.25em 0 0.5em\"\u003eKey Features\u003c\/h3\u003e\n\u003ctable class=\"pu-table\" style=\"width:100%;border-collapse:separate;border-spacing:0;border:0;box-shadow:none;outline:none;background:none;table-layout:fixed;margin:0 0 1em\"\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eBrand\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eKeith Black Pistons\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eProduct Type\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eEngine Pistons\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003ePiston Top Style\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eFlat Top\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eOversize\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e+0.020 in\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eBore Size\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e89.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eStroke\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e108 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eMaterial\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eHypereutectic 16% Silicon Aluminum Alloy\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eCompression Ratio\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e8.6:1 (with 80cc combustion chamber)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eOEM Replacement Number\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e21943-83\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eEngine Compatibility\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003eAir-Cooled Evolution (Evo)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:0.4em 0.75em 0.4em 0;opacity:0.65;vertical-align:top\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:0.4em 0;vertical-align:top\"\u003e1.2 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\n\u003ch3 style=\"margin:1.25em 0 0.5em\"\u003eHighlights\u003c\/h3\u003e\n\u003cul style=\"margin:1em 0\"\u003e\n\u003cli\u003eCast hypereutectic 16% silicon alloy designed for air-cooled engines\u003c\/li\u003e\n\u003cli\u003eLow thermal expansion allows for tighter piston-to-cylinder clearance\u003c\/li\u003e\n\u003cli\u003eProvides an 8.6:1 compression ratio with 80cc cylinder heads\u003c\/li\u003e\n\u003cli\u003eDirect replacement for OEM # 21943-83\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 style=\"margin:1.25em 0 0.5em\"\u003eCompatibility\u003c\/h3\u003e\n\u003cp style=\"margin:1em 0\"\u003eFits Harley-Davidson Big Twin models from 1984 to 1999 equipped with the Evolution (Evo) engine.\u003c\/p\u003e\n\u003ch3 style=\"margin:1.25em 0 0.5em\"\u003eWhat's included\u003c\/h3\u003e\n\u003cul style=\"margin:1em 0\"\u003e\n\u003cli\u003e2 x Keith Black Flat Top Pistons\u003c\/li\u003e\n\u003cli\u003e1 x Piston Ring Set\u003c\/li\u003e\n\u003cli\u003e2 x Wrist Pins\u003c\/li\u003e\n\u003cli\u003e4 x Retaining Clips\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 style=\"margin:1.25em 0 0.5em\"\u003eDownloads\u003c\/h3\u003e\n\u003cul style=\"margin:1em 0\"\u003e\u003cli style=\"margin:0 0 0.35em\"\u003e\u003ca href=\"https:\/\/images.rolliesspeedshop.com\/pdf\/KB258.020.pdf\" target=\"_blank\" rel=\"noopener nofollow\"\u003eDownload Product information ( PDF)\u003c\/a\u003e\u003c\/li\u003e\u003c\/ul\u003e\n\u003ctable class=\"pu-table\" style=\"width:100%;border-collapse:separate;border-spacing:0;border:0;box-shadow:none;outline:none;background:none;table-layout:fixed;margin:0\"\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd style=\"border:0;padding:0\"\u003e\n\u003ch3 style=\"margin:1.25em 0 0.5em\"\u003eFrequently asked questions\u003c\/h3\u003e\n\u003cstyle\u003e.pu-faq[open]\u003esummary .pu-faq-c{transform:rotate(180deg)}\u003c\/style\u003e\n\u003ctable class=\"pu-table\" style=\"width:100%;border-collapse:separate;border-spacing:0;border:0;box-shadow:none;outline:none;background:none;table-layout:fixed;margin:0 0 1em\"\u003e\u003ctbody\u003e\n\u003ctr\u003e\u003ctd style=\"border:0;padding:0;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e\u003cdetails class=\"pu-faq\" style=\"padding:0.45em 0\"\u003e\u003csummary style=\"cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:10px;list-style:none\"\u003e\u003cstrong\u003eWhat is the compression ratio of these pistons?\u003c\/strong\u003e\u003csvg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"18\" height=\"18\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"1.75\" stroke-linecap=\"round\" stroke-linejoin=\"round\" class=\"pu-faq-c\" style=\"width:1em;height:1em;flex:none;opacity:0.6;transition:transform 0.15s\" aria-hidden=\"true\"\u003e\u003cpath d=\"M6 9l6 6l6 -6\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\u003c\/summary\u003e\u003cp style=\"margin:0.4em 0 0\"\u003eThese pistons provide an 8.6:1 compression ratio when used with an 80cc cylinder head chamber volume.\u003c\/p\u003e\u003c\/details\u003e\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd style=\"border:0;padding:0;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e\u003cdetails class=\"pu-faq\" style=\"padding:0.45em 0\"\u003e\u003csummary style=\"cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:10px;list-style:none\"\u003e\u003cstrong\u003eWhat components are included in the kit?\u003c\/strong\u003e\u003csvg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"18\" height=\"18\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"1.75\" stroke-linecap=\"round\" stroke-linejoin=\"round\" class=\"pu-faq-c\" style=\"width:1em;height:1em;flex:none;opacity:0.6;transition:transform 0.15s\" aria-hidden=\"true\"\u003e\u003cpath d=\"M6 9l6 6l6 -6\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\u003c\/summary\u003e\u003cp style=\"margin:0.4em 0 0\"\u003eThe complete kit includes two pistons, piston rings, wrist pins, and retaining clips.\u003c\/p\u003e\u003c\/details\u003e\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd style=\"border:0;padding:0;border-bottom:1px solid rgba(128,128,128,0.16);border-bottom:1px solid color-mix(in srgb,currentColor 12%,transparent)\"\u003e\u003cdetails class=\"pu-faq\" style=\"padding:0.45em 0\"\u003e\u003csummary style=\"cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:10px;list-style:none\"\u003e\u003cstrong\u003eWhat OEM part number do these pistons replace?\u003c\/strong\u003e\u003csvg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"18\" height=\"18\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"1.75\" stroke-linecap=\"round\" stroke-linejoin=\"round\" class=\"pu-faq-c\" style=\"width:1em;height:1em;flex:none;opacity:0.6;transition:transform 0.15s\" aria-hidden=\"true\"\u003e\u003cpath d=\"M6 9l6 6l6 -6\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\u003c\/summary\u003e\u003cp style=\"margin:0.4em 0 0\"\u003eThese pistons replace OEM part number 21943-83.\u003c\/p\u003e\u003c\/details\u003e\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd style=\"border:0;padding:0\"\u003e\u003cdetails class=\"pu-faq\" style=\"padding:0.45em 0\"\u003e\u003csummary style=\"cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:10px;list-style:none\"\u003e\u003cstrong\u003eWhat material is used in the construction of these pistons?\u003c\/strong\u003e\u003csvg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 24 24\" width=\"18\" height=\"18\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"1.75\" stroke-linecap=\"round\" stroke-linejoin=\"round\" class=\"pu-faq-c\" style=\"width:1em;height:1em;flex:none;opacity:0.6;transition:transform 0.15s\" aria-hidden=\"true\"\u003e\u003cpath d=\"M6 9l6 6l6 -6\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\u003c\/summary\u003e\u003cp style=\"margin:0.4em 0 0\"\u003eThey are manufactured from a hypereutectic alloy containing 16% cast silicon for reduced thermal expansion in air-cooled engines.\u003c\/p\u003e\u003c\/details\u003e\u003c\/td\u003e\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\n\u003c\/td\u003e\u003c\/tr\u003e\u003c\/tbody\u003e\u003c\/table\u003e","brand":"Keith Black Pistons","offers":[{"title":"Default Title","offer_id":49680890986752,"sku":"KB258.020","price":566.15,"currency_code":"NZD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0855\/0888\/2688\/files\/KB258.020.jpg?v=1788494442","url":"https:\/\/baychoppers.co.nz\/products\/keith-black-pistons-flat-top-pistons-kb258-020-for-big-twin-1984-1999","provider":"Bay Choppers NZ","version":"1.0","type":"link"}