{"product_id":"yamaha-yfm-1-00-rings-yfm-350-yfm-400-f-fw-fb-os-1-00-1987-2011","title":"Yamaha OS 1.00 Piston Ring Kit Fits YFM 350 And YFM 400 F FW FB Engines 1987 To 2011","description":"\u003cdiv\u003e\n\u003cp\u003eA precise OS 1.00 oversize piston ring kit designed for single-cylinder 350\/400cc ATV engines from 1987 through 2011, this kit restores compression by sealing a bore worn from years of hard off-road use. It targets the exact ring set sizing needed to reestablish peak power and efficient combustion in older, high-demand quads, without the need to source OEM parts. This aftermarket replacement provides a cost-effective, reliable rebuild option for trail riding or farm work where every horsepower matters.\u003c\/p\u003e\n\u003cp\u003eBuilt to withstand dusty, hot, and vibrating environments, this OS 1.00 kit reclaims lost compression and reduces oil consumption by renewing the piston-to-bore seal. Its oversize design compensates for bore wear, delivering consistent ring tension and durable performance when you’re rebuilding a single-cylinder powerplant in your utility ATV. For riders and farmers who depend on dependable engine restoration, this kit offers a trustworthy balance of fit, function, and value.\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\u003eYFM350ER\u003c\/td\u003e\n\u003ctd\u003e1987 - 2000\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350U\u003c\/td\u003e\n\u003ctd\u003e1987 - 2000\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350F\u003c\/td\u003e\n\u003ctd\u003e1987 - 1999\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350FW\u003c\/td\u003e\n\u003ctd\u003e1987 - 1999\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350FX\u003c\/td\u003e\n\u003ctd\u003e1987 - 2009\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350X\u003c\/td\u003e\n\u003ctd\u003e1987 - 2009\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350G\u003c\/td\u003e\n\u003ctd\u003e2007 - 2010\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM350R\u003c\/td\u003e\n\u003ctd\u003e2004 - 2009\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM400F\u003c\/td\u003e\n\u003ctd\u003e1993 - 2006\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM400FW\u003c\/td\u003e\n\u003ctd\u003e1993 - 2006\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYFM400FB\u003c\/td\u003e\n\u003ctd\u003e2007 - 2011\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eFitment data is based on OEM and aftermarket listings for the YFM 350\/400 series engines spanning 1987-2011.\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\u003e4GB-11610-40-00\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003ePiston Ring Kit (OS 1.00)\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\u003eYFM 350\/400 series engines, 1987-2011\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eTop ring: cast iron with chromium facing; second\/oil rings: chrome-coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOversize\u003c\/td\u003e\n\u003ctd\u003e+1.00 mm (OS 1.00)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCylinder Count\u003c\/td\u003e\n\u003ctd\u003e1-cylinder per engine\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 ring\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePackage Quantity\u003c\/td\u003e\n\u003ctd\u003e1 piston ring set per engine\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\u003e4GB-11610-40-00\u003c\/td\u003e\n\u003ctd\u003eOEM Yamaha Piston Ring Set (1.00 MM O\/S)\u003c\/td\u003e\n\u003ctd\u003eOS 1.00 matching aftermarket replacement\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e4GB-11610-00-00\u003c\/td\u003e\n\u003ctd\u003eOEM Yamaha Piston Ring Set (STD)\u003c\/td\u003e\n\u003ctd\u003eStandard bore reference\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e4GB-11610-20-00\u003c\/td\u003e\n\u003ctd\u003eOEM Yamaha Piston Ring Set (0.50 MM O\/S)\u003c\/td\u003e\n\u003ctd\u003e0.50 mm oversize reference\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\u003eAll the essential rings needed to restore sealing on a single YFM 350\/400 cylinder with OS 1.00 sizing:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eTop compression ring\u003c\/b\u003e (OS 1.00)\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eSecond compression ring\u003c\/b\u003e (OS 1.00)\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOil control ring set\u003c\/b\u003e (OS 1.00)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: Piston, wrist pin, circlips, and gaskets are not included in this kit.\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 for YFM 350\/400 engines to restore original compression and power.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOEM Cross-Reference:\u003c\/b\u003e Cross-referenced to Yamaha part 4GB-11610-40-00, ensuring reliable compatibility with OEM specifications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePremium Materials:\u003c\/b\u003e Durable cast iron with chromium facing on the top ring and chrome-coated secondary rings for wear resistance in dusty, high-heat environments.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOversize Precision:\u003c\/b\u003e +1.00 mm oversize to correct bore wear and re-seal the combustion chamber effectively.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eReliability in Hard-Duty Use:\u003c\/b\u003e Built to withstand trail abuse and farm grit, delivering consistent sealing and longer service life.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCost-Effective Rebuild:\u003c\/b\u003e A practical solution to restore performance without the expense of OEM-only sourcing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Notes:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eInspect the bore:\u003c\/b\u003e Before installation, measure bore wear and confirm OS size suitability for the rebuild.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eCleanliness matters:\u003c\/b\u003e Thoroughly clean the cylinder and oil passages; remove all grit and carbon before ring installation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRings handling:\u003c\/b\u003e Use a proper ring expander or appropriate tool to avoid nicking the rings; keep rings flat and unbent.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eLubrication:\u003c\/b\u003e Lightly lubricate all rings with clean engine oil to ease installation and seating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRing orientation:\u003c\/b\u003e Install the top ring with the correct face orientation and stagger end gaps away from each other to prevent blow-by.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eRing seating \u0026amp; inspection:\u003c\/b\u003e After assembly, perform a compression test and inspect for blow-by or uneven seating during initial startup.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Upgrade?\u003c\/h3\u003e\n\u003cp\u003eRunning a worn piston ring set can dramatically reduce compression, increase oil consumption, and steal power. Upgrading to this OS 1.00 oversized kit restores sealing, improves compression, and returns the engine’s performance and reliability for trail and farm duty alike. It’s a practical rebuild choice when bore wear has begun impacting daily operation.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"ATV City","offers":[{"title":"Default Title","offer_id":57319264649590,"sku":"192.04815","price":19.33,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0971\/0302\/0406\/files\/pistonring.png?v=1774886127","url":"https:\/\/dgtagri.co.uk\/products\/yamaha-yfm-1-00-rings-yfm-350-yfm-400-f-fw-fb-os-1-00-1987-2011","provider":"DGT Agri","version":"1.0","type":"link"}