{"product_id":"piston-ring-kit-yamaha-yfb-yfm-250-os-0-50-1989-2009","title":"Piston Ring Kit OS 0.50 Oversize for Yamaha YFB and YFM 250cc Four Stroke Bear Tracker Bruin 1989 to 2009","description":"\u003cp\u003eThis OS 0.50 oversize piston ring kit is a direct-fit restoration solution for a 250cc four-stroke engine family used in trail-ready utility quads. It restores compression and oil control by renewing worn rings, delivering smoother starts and more confident power for rough terrain. With an OS 0.50 oversize designed to compensate mildly worn bores, this kit provides a cost-effective upgrade without OEM branding.\u003c\/p\u003e\n\u003cp\u003eIdeal for riders tackling dusty trails and farm workloads, this aftermarket replacement addresses common wear that leads to blow-by, increased oil consumption, and loss of punch. The OS 0.50 oversize re-establishes sealing in mildly worn bores, helping restore throttle response, reduce smoking, and sustain reliable starts in Bear Tracker and Bruin engines for miles of hard-use performance.\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\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\u003eYFM250\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\u003eYFM250B (Bruin)\u003c\/td\u003e\n\u003ctd\u003e2005–2009\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\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\u003e4BD-11610-20-00 (OS 0.50); 4BD-11610-00 (STD 71.0mm); 4BD-11610-40 (OS 1.00)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003ePiston Ring Kit\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\u003eYFB\/YFM 250cc four-stroke engines (1989–2009)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRing Stack\u003c\/td\u003e\n\u003ctd\u003eTop Ring, Second Ring, Oil Ring (3-piece set)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBore Size (STD)\u003c\/td\u003e\n\u003ctd\u003e71.0 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOversize\u003c\/td\u003e\n\u003ctd\u003eOS +0.50 mm (71.50 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTop Ring Material\u003c\/td\u003e\n\u003ctd\u003eChrome Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecond Ring Material\u003c\/td\u003e\n\u003ctd\u003eCast Iron\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOil Ring Material\u003c\/td\u003e\n\u003ctd\u003eStainless Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eExact Oversize\u003c\/td\u003e\n\u003ctd\u003eOS 0.50 mm\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\u003e4BD-11610-20-00\u003c\/td\u003e\n\u003ctd\u003eYamaha OEM\u003c\/td\u003e\n\u003ctd\u003eOS 0.50 Piston Ring Set for YFB\/YFM 250; matches +0.50 oversize bore applications\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e4BD-11610-00\u003c\/td\u003e\n\u003ctd\u003eYamaha OEM\u003c\/td\u003e\n\u003ctd\u003eSTD 71.0 mm Piston Ring Set; base specification for the 71.0 mm bore family\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e4BD-11610-40\u003c\/td\u003e\n\u003ctd\u003eYamaha OEM\u003c\/td\u003e\n\u003ctd\u003eOS 1.00 mm; alternative oversize for more bore wear\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e2815XC\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003ctd\u003ePiston Rings for Yamaha YFB\/YFM 250; Bore 71.50 mm; OS +0.50; common cross-reference for +0.50 overbores\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 provides the essential components needed to restore piston sealing on the Yamaha 250 family. \u003cbr\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cb\u003ePiston Ring Set – Top Ring\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003ePiston Ring Set – Second Ring\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003ePiston Ring Set – Oil Ring\u003c\/b\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003ci\u003eNote: Piston, wrist pin, and circlips are not included.\u003c\/i\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 4BD bore family with STD and oversize options to fit worn engines without modification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOEM Cross-Reference Clarity:\u003c\/b\u003e Clear cross-references to Yamaha OEM numbers ensure you’re selecting a true substitution that aligns with dealer catalogs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePremium Materials:\u003c\/b\u003e Top ring in chrome steel, second ring in cast iron, and oil ring in stainless steel deliver durable wear resistance and reliable oil control.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePerformance Restoration:\u003c\/b\u003e The OS 0.50 oversize re-establishes sealing in mildly worn bores, helping reclaim compression and throttle response.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRugged Reliability for Tough Duty:\u003c\/b\u003e Built to withstand dust, mud, and extended trail or farm use while maintaining seals over time.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCost-Effective Replacement:\u003c\/b\u003e A value-driven option that preserves engine life without the premium OEM price tag.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Notes:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003ePrep the bore:\u003c\/b\u003e Inspect and measure the cylinder bore to confirm STD 71.0 mm or 71.50 mm with OS 0.50; clean the bore thoroughly before installation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRing orientation:\u003c\/b\u003e Ensure proper orientation of the top and second rings and stagger ring end gaps in the ring stack to minimize blow-by.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRing compression:\u003c\/b\u003e Use an appropriate ring compressor sized for a 71.5 mm bore to avoid ring damage during installation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eLubrication:\u003c\/b\u003e Lightly oil all rings before installation and lubricate the piston crown and skirt as you assemble to reduce dry start wear.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eEnd-gap checks:\u003c\/b\u003e After installation, verify end gaps per service manual guidelines and adjust if required.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eBreak-in procedure:\u003c\/b\u003e After startup, avoid excessive load for the first 15–20 minutes; vary engine RPM to seat the rings gradually.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Upgrade?\u003c\/h3\u003e\n\u003cp\u003eRunning a worn piston ring in this 250cc four-stroke family invites continued compression loss, increased oil consumption, and smoky starts. This OS 0.50 oversize kit restores sealing efficiency and oil control, returning dependable power and smoother operation for trail or farm work.\u003c\/p\u003e","brand":"ATV City","offers":[{"title":"Default Title","offer_id":57319264420214,"sku":"192.04803","price":15.33,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0971\/0302\/0406\/files\/pistonring_640933fd-14df-4ac3-9bda-c13cbabfc4b5.png?v=1774886130","url":"https:\/\/dgtagri.co.uk\/products\/piston-ring-kit-yamaha-yfb-yfm-250-os-0-50-1989-2009","provider":"DGT Agri","version":"1.0","type":"link"}