{"product_id":"piston-kit-honda-trx-420-os-0-50-2007-23","title":"Piston Kit OS 0.50 Honda TRX 420 2007 Through 2023 OEM Replacement Fits TRX 420 Models","description":"\u003cdiv\u003e\n\u003cp\u003eThis OS oversize piston kit (+0.50 mm) is built for the Honda TRX 420 Rancher family (2007–2023) to restore lost compression and bring back strong top‑end power with solid mid‑range torque. Engineered as an aftermarket replacement, it delivers reliable, consistent power for trail miles and demanding work‑site use, without jumping to a larger bore kit. By refreshing the bore with a precise +0.50 mm oversize, this kit helps maintain a durable seal and smooth operation across the TRX 420 lineup.\u003c\/p\u003e\n\u003cp\u003eDesigned for riders who push their Rancher hard, this kit focuses on reclaiming throttle response and daily reliability after top‑end wear. It’s a practical rebuild solution that preserves factory geometry and keeps the engine performing consistently under load—whether you’re tackling rugged trails, forestry work, or farm duties. The result is a dependable restoration that avoids the jump to a larger bore while delivering noticeable power and torque gains.\u003c\/p\u003e\n\u003ch3\u003eComprehensive Vehicle Fitment\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eManufacturer\u003c\/th\u003e\n\u003cth\u003eModels \/ Series\u003c\/th\u003e\n\u003cth\u003eYears \/ Details\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420FA1 Rancher 4x4 Auto\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420FA2 Rancher 4x4 Auto EPS\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420FA5\/FA6 Rancher 4x4 Auto IRS\u003c\/td\u003e\n\u003ctd\u003e2015–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420FE1 Rancher 4x4 ES\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420FM1 Rancher 4x4\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420FM2 Rancher 4x4 EPS\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420TE1 Rancher 2x4 ES\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX420TM1 Rancher 2x4\u003c\/td\u003e\n\u003ctd\u003e2014–2024\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3\u003eProduct Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eAttribute\u003c\/th\u003e\n\u003cth\u003eDetails\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eOEM Reference Part Numbers\u003c\/td\u003e\n\u003ctd\u003e13103-HP5-600\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003ePiston Kit OS Oversize +0.50\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eManufacturer\u003c\/td\u003e\n\u003ctd\u003eAftermarket Replacement\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eHonda TRX 420 Rancher models (2007–2023)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eForged aluminum piston (typical industry construction for oversize kits)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBore Size\u003c\/td\u003e\n\u003ctd\u003e87.0 mm (oversize +0.50 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStandard Bore\u003c\/td\u003e\n\u003ctd\u003e86.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStroke\u003c\/td\u003e\n\u003ctd\u003e71.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDisplacement\u003c\/td\u003e\n\u003ctd\u003e425 cc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePiston Ring Set\u003c\/td\u003e\n\u003ctd\u003eIncluded (top and second compression rings + oil ring)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePiston Pin \/ Circlips\u003c\/td\u003e\n\u003ctd\u003eIncluded (wrist pin and retaining clips typical of kits)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3\u003eOEM \u0026amp; Aftermarket Cross-Reference Information\u003c\/h3\u003e\n\u003ctable style=\"width: 100%;\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth style=\"width: 20.9386%;\"\u003ePart Number\u003c\/th\u003e\n\u003cth style=\"width: 18.9357%;\"\u003eBrand \/ Type\u003c\/th\u003e\n\u003cth style=\"width: 59.4037%;\"\u003eCross-Reference Notes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"width: 20.9386%;\"\u003e13103-HP5-600\u003c\/td\u003e\n\u003ctd style=\"width: 18.9357%;\"\u003eHonda OEM Piston Kit\u003c\/td\u003e\n\u003ctd style=\"width: 59.4037%;\"\u003eOEM reference for TRX 420; aftermarket OS kit serves as a direct replacement with +0.50 mm oversize.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"width: 20.9386%;\"\u003e40050M08700\u003c\/td\u003e\n\u003ctd style=\"width: 18.9357%;\"\u003eWiseco Piston Kit (ArmorGlide)\u003c\/td\u003e\n\u003ctd style=\"width: 59.4037%;\"\u003e87.00 mm bore (+0.50 mm oversize) for Honda TRX 420 Rancher (07–15). Common aftermarket cross-reference for +0.50 oversize builds.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"width: 20.9386%;\"\u003e50-231-09K\u003c\/td\u003e\n\u003ctd style=\"width: 18.9357%;\"\u003eWSM Piston Kit\u003c\/td\u003e\n\u003ctd style=\"width: 59.4037%;\"\u003eExamples show +1.5 mm oversize variants for TRX 420; included here as a cross-reference note for context (not the exact oversize in this kit).\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3\u003eWhat’s Included\u003c\/h3\u003e\n\u003cp\u003eThis OS oversize piston kit arrives with the essential components needed to rebuild the top end and restore performance. \u003cbr\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003ePiston\u003c\/b\u003e with +0.50 mm oversize bore\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePiston Ring Set\u003c\/b\u003e matching the oversize piston\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePiston Pin \/ Wrist Pin\u003c\/b\u003e and \u003cb\u003eCirclips\u003c\/b\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eInstall Lubricant\u003c\/b\u003e (small quantity for initial startup, if included by manufacturer)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: Gaskets, head cover seals, and other related seals\/gaskets are not included and may require separate gasket sets depending on your rebuild scope.\u003c\/em\u003e\u003c\/p\u003e\n\u003ch3\u003eWhy Choose This Aftermarket Replacement?\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eDirect-Fit Compatibility:\u003c\/b\u003e Precisely matched to the TRX 420 top end geometry for a clean, vibration‑free installation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOEM Cross-Reference:\u003c\/b\u003e Uses the OEM reference as a validation point while delivering a cost‑effective aftermarket alternative.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePremium Materials:\u003c\/b\u003e Forged aluminum piston with a durable ring set designed for consistent power delivery under load.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eThorough Rebuild Performance:\u003c\/b\u003e Restores compression and throttle response without the need for a larger bore upgrade.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eReliable Across TRX 420 Line:\u003c\/b\u003e Backed by compatibility across multiple Rancher configurations and years within the 2007–2023 window.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eDurable Top End Restoration:\u003c\/b\u003e Engineered to endure trail work and farm duties with stable, repeatable performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Notes:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eInspect the cylinder bore for scoring or damage; hone as required before installing the oversize piston.\u003c\/li\u003e\n\u003cli\u003eLubricate the wrist pin and rings with assembly lube prior to installation to reduce initial dry startup wear.\u003c\/li\u003e\n\u003cli\u003eInstall the piston rings with the gaps offset as per standard practice to minimize blow‑by and oil fouling.\u003c\/li\u003e\n\u003cli\u003eUse new circlips and ensure they seat fully in the piston grooves to prevent wrist pin movement.\u003c\/li\u003e\n\u003cli\u003eVerify ring end gaps are within the manufacturer’s specified range after installation and before startup.\u003c\/li\u003e\n\u003cli\u003eFollow torque and assembly specifications for surrounding components during reassembly and perform a proper break‑in procedure.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Upgrade?\u003c\/h3\u003e\n\u003cp\u003eRunning a worn top end on the TRX 420 can lead to compression loss, reduced throttle response, and uneven power delivery, especially under load. This OS oversize piston kit restores compression, refreshes sealing, and recaptures reliable power output, returning the engine to predictable, daily‑drivable performance. It’s a practical path to regain factory‑like reliability without stepping up to a larger bore.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"ATV City","offers":[{"title":"Default Title","offer_id":57319260193142,"sku":"190.10042-2","price":98.33,"currency_code":"GBP","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0971\/0302\/0406\/files\/image_2026-02-25_223506773.png?v=1772058914","url":"https:\/\/dgtagri.co.uk\/products\/piston-kit-honda-trx-420-os-0-50-2007-23","provider":"DGT Agri","version":"1.0","type":"link"}