{"product_id":"dhm-high-compression-stock-bore-piston-kit-gen-2-honda-grom-monkey-2014-2020","title":"DHM High Compression Stock Bore Piston Kit (Gen 2) – Honda Grom \u0026 Monkey (2014–2020)","description":"\u003ch2\u003eDHM Race-Spec High Compression Stock Bore Piston Kit – Honda Grom \u0026amp; Monkey\u003c\/h2\u003e\u003cp\u003eThe highest compression stock bore piston on the market — and the only one with this dome design, made exclusively for DHMotoring. After 6 years of racetrack testing and over a dozen stock bore pistons evaluated, DHM engineered this Gen 2 piston to push the absolute limits of pump fuel compression while maximizing lubrication and long-term reliability at high RPM.\u003c\/p\u003e\u003cp\u003eNo other stock bore piston has produced more HP on the Honda Grom. If you’re building the most competitive 125cc engine possible, this is your foundation.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e~13.2:1 compression ratio\u003c\/li\u003e\n\u003cli\u003e52.4mm stock bore diameter\u003c\/li\u003e\n\u003cli\u003eLarger ring and skirt oiling holes than competing pistons\u003c\/li\u003e\n\u003cli\u003eLarger oil spring for increased oil volume between oiling rings\u003c\/li\u003e\n\u003cli\u003eOil ports under pin holes to keep the wrist pin lubricated at all RPM\u003c\/li\u003e\n\u003cli\u003e360° skirt design for increased overall strength\u003c\/li\u003e\n\u003cli\u003eValve reliefs sized for valves up to 27.5mm \/ 23.5mm — compatible with the highest lift cams on the market\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eWhat’s Included\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eDHM Race-Spec high compression piston\u003c\/li\u003e\n\u003cli\u003eRacing piston ring kit with pins and circlips\u003c\/li\u003e\n\u003cli\u003eNew base gasket and head gasket\u003c\/li\u003e\n\u003cli\u003eOptional: NGK CR9E (6263) spark plug\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eRequirements\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMinimum 91 octane fuel required\u003c\/li\u003e\n\u003cli\u003eNGK CR9E (6263) spark plug required\u003c\/li\u003e\n\u003cli\u003eCylinder NOT included — piston kit only\u003c\/li\u003e\n\u003cli\u003eRing gaps must be set before installation (see instructions below)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eHonda Grom OG (2014–2015)\u003c\/li\u003e\n\u003cli\u003eHonda Grom SF (2017–2020)\u003c\/li\u003e\n\u003cli\u003eHonda Monkey 1st Gen (2018–2021)\u003c\/li\u003e\n\u003cli\u003eHonda Super Cub (compatible)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eInstallation Notes\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eInstalling this piston requires setting the ring gaps. If you are not comfortable with this process, have your local shop perform the install. Failure to set proper ring end gap can result in premature failure or engine seizure.\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eRecommended end gaps: \u003cstrong\u003e.007–.009\"\u003c\/strong\u003e on the top ring — \u003cstrong\u003e.009–.011\"\u003c\/strong\u003e on the bottom ring. The silver ring goes on top, the black ring below. Watch the install video below for a full walkthrough.\u003c\/p\u003e\u003cdiv class=\"rte__video-wrapper\"\u003e\u003ciframe width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/LlQNSwmadaA\"\u003e\u003c\/iframe\u003e\u003c\/div\u003e","brand":"DHMotoring","offers":[{"title":"Yes","offer_id":44071066435825,"sku":"DHM-HCSBP-OGSF","price":126.0,"currency_code":"USD","in_stock":false},{"title":"No","offer_id":44071066468593,"sku":"DHM-HCSBP-OGSF-2","price":120.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0626\/1348\/7857\/products\/dhmotoring-piston-kit-yes-dhm-high-compression-stock-bore-piston-gen-2-2014-2020-grom-monkey-dhm-hcsbp-ogsf-66435825-29960307376369.webp?v=1773628655","url":"https:\/\/howlingmoto.com\/products\/dhm-high-compression-stock-bore-piston-kit-gen-2-honda-grom-monkey-2014-2020","provider":"Howling Moto","version":"1.0","type":"link"}