{"product_id":"piston-kit-yamaha-yfm-400-fb-fw-manual-os-0-50","title":"Piston Kit OS 0.50 For Yamaha YFM 400 FB FW Manual 1993-2012 OEM Replacement Fits YFM 400 FB FW","description":"\u003cdiv class=\"ds-message _63c77b1\"\u003e\n\u003cdiv class=\"ds-markdown\"\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eIf you're tackling a top-end rebuild on your Yamaha YFM 400 FB or FW Manual from 1993 to 2012, this OS 0.50 piston ring kit is the precise aftermarket solution you need to restore lost compression and get your engine running like new again. Designed specifically for these rugged ATV models, it addresses the common wear that leads to reduced power and efficiency over years of trail riding or farm work. By swapping in this reliable oversize ring set, you'll regain that responsive throttle and prevent further engine strain, making it an essential upgrade for maintaining peak performance on demanding terrains.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eWhat sets this aftermarket piston ring kit apart is its ability to tackle the specific wear-and-tear issues like cylinder bore enlargement and ring seal degradation that plague high-mileage Yamaha YFM 400 engines, ensuring your machine doesn't let you down mid-ride. This replacement delivers a spot-on fit that mimics OEM standards while using enhanced materials to withstand the heat and stress of off-road conditions, making it a smart choice for both recreational riders and hardworking farmers. With its focus on durability and precise engineering, you'll experience smoother operation and extended engine life, all without the premium price of original equipment parts.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eComprehensive Vehicle Fitment\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cdiv class=\"ds-scroll-area _1210dd7 c03cafe9\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cspan\u003eManufacturer\u003c\/span\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cspan\u003eModels \/ Series\u003c\/span\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cspan\u003eYears \/ Details\u003c\/span\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYFM400FB Big Bear 400 IRS\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e2007–2011\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYFM400FW Kodiak 400 4x4\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e1993–2006\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYFM400F Kodiak 400 4x4\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e2000–2006\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYFM400 Big Bear 400 2WD\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e2000–2006\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYFM400 Series (related variants)\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e1995–2003\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e \u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eProduct Specifications\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cdiv class=\"ds-scroll-area _1210dd7 c03cafe9\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cspan\u003eAttribute\u003c\/span\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cspan\u003eDetails\u003c\/span\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eOEM Reference Part Numbers\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003e\u003cspan\u003e4GB-11636-00-00\u003c\/span\u003e\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eType\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003ePiston Ring Kit OS 0.50 (Oversize)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eManufacturer\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eAftermarket Replacement\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eApplication\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha YFM 400 FB \/ FW Manual (1993–2012)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eMaterial\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eHigh-strength aluminum alloy \/ Chrome-faced steel\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eBore Size (Final)\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e83.50 mm (from standard 83 mm)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eOversize\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e0.50 mm\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eCompression Ratio (Restored)\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eApprox. 9.2:1\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eRing Configuration\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eTop Ring, Second Ring, Oil Ring Set\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003eCondition\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e100% New Aftermarket\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e \u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eOEM \u0026amp; Aftermarket Cross-Reference Information\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cdiv class=\"ds-scroll-area _1210dd7 c03cafe9\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cspan\u003ePart Number\u003c\/span\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cspan\u003eBrand \/ Type\u003c\/span\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cspan\u003eCross-Reference Notes\u003c\/span\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e\u003cspan\u003e4GB-11636-00-00\u003c\/span\u003e\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha OEM\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eOriginal standard piston assembly reference; this ring kit is the correct oversize replacement for engines bored to +0.50mm\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e\u003cspan\u003e4GB-11610-20-00\u003c\/span\u003e\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eYamaha OEM\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eOEM reference for 0.50mm oversize rings; this kit is a direct aftermarket equivalent\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e\u003cspan\u003e192.04811\u003c\/span\u003e\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eAftermarket\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eInternal product code used by some suppliers for Yamaha 350\/400 ring kits\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e*\u003cspan\u003eOEM cross-reference numbers are provided for reference purposes only. These numbers indicate the lineage of oversize rings; always verify your final bore size (83.50mm) before ordering.\u003c\/span\u003e*\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eWhat's Included\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eThis OS 0.50 oversize piston ring kit ships with the essential components to rebuild one Yamaha YFM 400 cylinder.\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eTop Ring (Chrome-faced)\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eSecond Ring\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eOil Ring Set (including expander spacer)\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cem\u003e\u003cspan\u003eNote: This is a piston ring kit only. It does not include the piston, wrist pin, circlips, or gaskets.\u003c\/span\u003e\u003c\/em\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eWhy Choose This Aftermarket Replacement?\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003ePrecise Oversize Fit:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Specifically designed for engines that have been professionally overbored to a final size of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e83.50 mm\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e (OS 0.50), ensuring correct ring gap and optimal sealing.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eOEM Cross-Reference:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Follows the oversize progression of OEM rings, making it the logical choice for a professionally rebuilt cylinder corresponding to piston reference \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e4GB-11636-00-00\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eRestores Lost Compression:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e New, properly gapped rings restore cylinder pressure, directly addressing power loss, blow-by, and high oil consumption.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eDurable Construction:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Features a high-quality chrome-faced top ring for superior heat resistance and wear longevity, built to withstand the demands of high-RPM operation and tough terrain.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eComplete Ring Set:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Includes all three rings (top, second, and oil ring set) required for a complete and effective piston seal.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eCost-Effective Engine Refresh:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Delivers reliable performance at an aftermarket price, ideal for extending the life of your machine without a full OEM investment.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eInstallation Notes:\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eVerify Bore Size:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e This is critical. Confirm the engine cylinder has been professionally overbored to the final size of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e83.50 mm\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e before ordering. This kit is not for standard or other oversize bores.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eProfessional Machining Required:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e A proper overbore and hone by a qualified machine shop is essential for the new rings to seat correctly and achieve a long-lasting seal.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eCheck Ring End Gap:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Always measure and adjust ring end gaps according to the service manual specifications for the 83.50mm bore.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eLubricate During Assembly:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Lubricate the piston, rings, and cylinder wall with clean engine oil or assembly lube prior to installation.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eOrient Rings Correctly:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Ensure rings are installed with the correct orientation (if any) and that the ring gaps are staggered according to the service manual to prevent blow-by.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eFollow Service Manual:\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e Adhere to all torque specifications and break-in procedures outlined in the Yamaha service manual.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eWhy Upgrade?\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan\u003eWorn piston rings on a Yamaha 400cc quad lead to noticeable compression loss, reduced power, and increased oil consumption. This OS 0.50 oversize ring kit restores proper ring seal and oil control, renewing reliable power and smooth operation, and preventing the risk of a sudden failure on the trail or in the field.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan\u003eOrder your piston ring kit today and get back on the trail with confidence.\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"ATV City","offers":[{"title":"Default Title","offer_id":57319261372790,"sku":"190.40006-2","price":78.67,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0971\/0302\/0406\/files\/image_2026-02-25_213453308.png?v=1774886192","url":"https:\/\/dgtagri.co.uk\/products\/piston-kit-yamaha-yfm-400-fb-fw-manual-os-0-50","provider":"DGT Agri","version":"1.0","type":"link"}