{"product_id":"piston-ring-kit-yamaha-yfb-yfm-250-os-1-00-1989-2009","title":"OS 1.00 Piston Ring Kit for Yamaha YFB 250 and Yamaha YFM 250 Quad Engines 1989 To 2009","description":"\u003cp\u003eRestore peak compression and a reliable seal in your 250cc quad’s top end with the OS 1.00 piston ring kit. This oversized ring set is designed for engines with a 71.0 mm bore, covering model years from 1989 through 2009 to refresh power, throttle response, and oil-control on trail or farm work. The OS 1.00 specification targets bore wear, delivering consistent end gaps and strong ring tension for a dependable rebuild without paying OEM prices. Built for durability under heat and friction, this kit helps reclaim torque and smooth revs across the entire RPM range.\u003c\/p\u003e\n\u003cp\u003eWith a focus on real-world riding wear, this aftermarket replacement targets common wear problems like blow-by and oil consumption that creep in as the bore widens. Its precisely matched OS 1.00 rings deliver reliable sealing, improved ring-pack stability under load, and long-lasting performance for tough conditions, whether logging a long trail ride or pulling heavy loads on the farm. It brings a factory-like rebuild experience at a value-focused price point, making it a trusted choice for older builds where availability and parts pricing matter.\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\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM250 Timberwolf\u003c\/td\u003e\n\u003ctd\u003e1989–1991\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFB250 Bear Tracker\u003c\/td\u003e\n\u003ctd\u003e1992–2000\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFB250F\u003c\/td\u003e\n\u003ctd\u003e1992–2000\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFB250U\u003c\/td\u003e\n\u003ctd\u003e1992–2000\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM250X\u003c\/td\u003e\n\u003ctd\u003e1999–2004\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM250B\u003c\/td\u003e\n\u003ctd\u003e2005–2009\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eSource notes: model coverage aligns with Yamaha 250cc quad lineups spanning late 1980s through the late 2000s, including Timberwolf, Bear Tracker, and related variants.\u003c\/p\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\u003e4BD-11610-40-00 (OS 1.00)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003ePiston Ring Set (oversize)\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\u003eYamaha YFM\/YFB 250 (1989–2009); OS 1.00 oversized rings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eSteel alloy piston ring set; OEM-style finish\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBore Compatibility\u003c\/td\u003e\n\u003ctd\u003eStandard bore 71.0 mm; oversize +1.00 mm (72.0 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNumber of Rings\u003c\/td\u003e\n\u003ctd\u003e3 rings total (2 compression rings + 1 oil ring)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRing Gaps \/ Orientation\u003c\/td\u003e\n\u003ctd\u003eFactory-toleranced gaps; top and second compression rings beveled up; oil ring with correct spacer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEnd-Gap Type\u003c\/td\u003e\n\u003ctd\u003eOS 1.00 oversize rings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eNotes: OEM reference and OS sizing reflect common Yamaha service data for 71.0 mm bores and OS 1.00 ring sets used across the late 1980s to 2000s 250cc quad lineup.\u003c\/p\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\u003e4BD-11610-40-00\u003c\/td\u003e\n\u003ctd\u003eOEM Yamaha\u003c\/td\u003e\n\u003ctd\u003ePiston Ring Set (1.00 MM OS); cross-reference in aftermarket catalogs with OS 1.00 sizing\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e4BR-11610-40-00\u003c\/td\u003e\n\u003ctd\u003eAftermarket Replacement\u003c\/td\u003e\n\u003ctd\u003eOEM-equivalent; OS 1.00 spec commonly listed by aftermarket suppliers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eNotes: cross-reference references reflect typical interchangeability used in aftermarket catalogs for Yamaha 250cc quad rings sets; confirm local supplier listings for exact cross-reference naming.\u003c\/p\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cp\u003eA compact, ready-to-install kit designed for a straightforward piston-ring upgrade. Includes:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cb\u003eTop Compression Ring\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003eSecond Compression Ring\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003eOil Ring\u003c\/b\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: Piston pin and circlips are not included with this ring kit. Separate components such as the pin (e.g., 29U-11633-00) and circlips may be required for complete assembly.\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 OS 1.00 rings designed to seal Yamaha YFM\/YFB 250 cylinders without modification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOEM Cross-Reference:\u003c\/b\u003e Backed by cross-reference with Yamaha part numbers to ensure reliable interchangeability across markets.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePremium Materials:\u003c\/b\u003e Robust steel alloy construction with OEM-style finishes to resist heat and wear in high-load applications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePerformance Restoration:\u003c\/b\u003e Restores compression and ring-end stability, improving throttle response and torque across the rev range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCost-Effective Value:\u003c\/b\u003e A practical rebuild option that delivers OEM-like performance without OEM pricing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eAvailability for Older Builds:\u003c\/b\u003e Specifically suited for mid-to-late 1990s–2000s models where OEM stock may be scarce.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Notes:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eCheck bore wear before install:\u003c\/b\u003e verify the 71.0 mm standard bore and confirm OS 1.00 sizing necessity for your cylinder.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRing orientation matters:\u003c\/b\u003e install the top and second compression rings with bevel facing up; ensure the oil ring spacer is seated correctly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePre-lubricate:\u003c\/b\u003e apply assembly lube to all rings and mating surfaces to minimize installation scuffing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eClean grooves and decks:\u003c\/b\u003e thoroughly clean ring grooves and the piston crown to prevent binding or micro-gaps.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eDouble-check end gaps:\u003c\/b\u003e confirm gaps meet OEM-style tolerances to avoid ring sticking or blow-by on startup.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eUse correct torque and assembly steps:\u003c\/b\u003e follow shop manual guidelines for piston ring end-gap orientation and ring seating after initial startup.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Upgrade?\u003c\/h3\u003e\n\u003cp\u003eRunning a worn piston-ring set leads to blow-by, reduced compression, and increased oil consumption, especially under heavy throttle and load. Replacing with an OS 1.00 kit restores seal integrity, reclaiming power and reliability for long trail sessions or field chores.\u003c\/p\u003e","brand":"ATV City","offers":[{"title":"Default Title","offer_id":57319264485750,"sku":"192.04805","price":15.33,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0971\/0302\/0406\/files\/pistonring_1fc364e4-7278-43db-b52b-80d77ece43b1.png?v=1774886131","url":"https:\/\/dgtagri.co.uk\/products\/piston-ring-kit-yamaha-yfb-yfm-250-os-1-00-1989-2009","provider":"DGT Agri","version":"1.0","type":"link"}