{"product_id":"piston-ring-kit-honda-trx-450-os-0-25-1998-2004","title":"Piston Ring Kit OS 0.25 For Honda TRX 450 Foreman 1998 1999 2000 2001 2002 2003 2004 TEIKOKU Material","description":"\u003cdiv\u003e\n\u003cp\u003eEngine restoration that makes the TRX450 Foreman feel new again starts with a Precision Piston Ring Kit OS 0.25. This aftermarket replacement is designed for Honda TRX450 Foreman models from 1998 through 2004 and uses a TEIKOKU ring material to closely match OE performance. Sized for a standard 90 mm bore upgraded to 90.25 mm, it reestablishes compression, improves sealing, and keeps the engine breathing clean in dusty trail rides or hard farm work.\u003c\/p\u003e\n\u003cp\u003eThese OS 0.25 rings tackle common wear issues that plague high-mileage TRX450 Foreman engines: worn grooves, seal leaks, and end-gap drift that allow oil blow-by and compression loss. By restoring ring tension and sealing, this kit helps recover top-end power and reliability without the cost of OEM-only parts, making it a practical choice for trail machines and workhorse farms alike.\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\u003eTRX450 Foreman (S\/ES\/FE\/FM)\u003c\/td\u003e\n\u003ctd\u003e1998–2004, 0.25 OS piston ring kit for TRX450 Foreman engines\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX450 Foreman FM\u003c\/td\u003e\n\u003ctd\u003e1998–2004, 0.25 OS piston ring set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX450 Foreman FE\u003c\/td\u003e\n\u003ctd\u003e1998–2004, 0.25 OS piston ring set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX450 Foreman ES\u003c\/td\u003e\n\u003ctd\u003e1998–2004, 0.25 OS piston ring set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHonda\u003c\/td\u003e\n\u003ctd\u003eTRX450 Foreman S\u003c\/td\u003e\n\u003ctd\u003e1998–2004, 0.25 OS piston ring set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\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\u003e13011-HN0-A01; 13011-HN0-A02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003ePiston Ring Kit (0.25 OS)\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\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eTEIKOKU piston ring material (OEM-equivalent)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBore Size\u003c\/td\u003e\n\u003ctd\u003eStandard 90 mm; Oversize to 90.25 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRings Included\u003c\/td\u003e\n\u003ctd\u003eTop compression ring; Second compression ring; Oil control ring\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOversize\u003c\/td\u003e\n\u003ctd\u003e0.25 OS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003c\/h3\u003e\n\u003ch3\u003eOEM \u0026amp; Aftermarket Cross-Reference Information\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003ePart Number\u003c\/th\u003e\n\u003cth\u003eBrand \/ Type\u003c\/th\u003e\n\u003cth\u003eCross-Reference Notes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e13011-HN0-A01\u003c\/td\u003e\n\u003ctd\u003eTEIKOKU (OEM)\u003c\/td\u003e\n\u003ctd\u003e0.25 OS piston ring set for TRX450 Foreman; TEIKOKU material\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e13011-HN0-A02\u003c\/td\u003e\n\u003ctd\u003eTEIKOKU (OEM)\u003c\/td\u003e\n\u003ctd\u003eAlternate TEIKOKU packaging for 0.25 OS; widely used in shipments\/catalogs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e13010-HN0-A01\u003c\/td\u003e\n\u003ctd\u003eTEIKOKU (OEM STD)\u003c\/td\u003e\n\u003ctd\u003eStandard bore piston ring set (STD); used as cross-reference\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e13011-HN0-A02\u003c\/td\u003e\n\u003ctd\u003eRIKEN (Cross-Reference)\u003c\/td\u003e\n\u003ctd\u003e0.25 OS variant cross-referenced by some suppliers as RIKEN alternative\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003c\/h3\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cp\u003eThis kit includes the essential piston rings that restore compression and sealing for the TRX450 Foreman.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cb\u003eTop compression ring\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003eSecond compression ring\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003eOil control ring\u003c\/b\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: Related components such as a piston, piston pin, circlips, base gaskets, or cylinder head gaskets are not included with this ring set.\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 sized for 90 mm standard bore, upgraded to 90.25 mm, matching the TRX450 Foreman engine geometry.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOEM Cross-Reference:\u003c\/b\u003e TEIKOKU material used to mirror OE performance; recognized in multiple catalogs as the 0.25 OS option (13011-HN0-A01 \/ A02).\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePremium Materials (Piston Ring):\u003c\/b\u003e TEIKOKU-grade ring material chosen for durability and reliable sealing in dusty, heavy-use environments.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePerformance Restoration:\u003c\/b\u003e Restores compression and reduces oil blow-by after bore wear, improving power delivery and top-end response.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCost-Effective Reliability:\u003c\/b\u003e A practical aftermarket path to TRX450 Foreman reliability without OEM-only constraints.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCompatibility Assurance:\u003c\/b\u003e Verified cross-references align with TRX450 Foreman variants (S\/ES\/FE\/FM) across 1998–2004 models.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Notes:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eInspect bore and ring grooves:\u003c\/b\u003e If bore wear exceeds service limits, consider reboring to the next oversize and use the matching OS rings.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eClean grooves and bores thoroughly:\u003c\/b\u003e Remove carbon and debris to prevent ring stiction and uneven sealing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCheck ring orientation:\u003c\/b\u003e Install rings with markings facing up and keep top vs. second rings separated to avoid mixing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eEnd-gap staggering:\u003c\/b\u003e Space ring end gaps approximately 120 degrees apart to promote even oil control and sealing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eLubricate during assembly:\u003c\/b\u003e Apply a light coat of clean engine oil to rings and bore before installation to ease seating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eFollow OEM service limits:\u003c\/b\u003e When measuring end gaps and bores, use service limits from the TRX450 manual to ensure proper clearance after installation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Upgrade?\u003c\/h3\u003e\n\u003cp\u003eRunning a worn piston ring set in a TRX450 Foreman can allow oil to bypass the rings, leading to reduced compression, higher oil consumption, and degraded throttle response. This OS 0.25 kit reestablishes the seal and ring tension, delivering restored compression and reliable power for trail duty or fieldwork.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"ATV City","offers":[{"title":"Default Title","offer_id":57319262290294,"sku":"192.04542","price":24.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0971\/0302\/0406\/files\/pistonring_59ab648e-64cb-4d75-839b-48640ef0d7c9.png?v=1774886132","url":"https:\/\/dgtagri.co.uk\/products\/piston-ring-kit-honda-trx-450-os-0-25-1998-2004","provider":"DGT Agri","version":"1.0","type":"link"}