{"product_id":"wossner-k8877d500-2-polaris-rzr-ranger-800-big-bore-forged-piston-kit-5-00mm","title":"WOSSNER K8877D500-2 Polaris RZR Ranger 800 Big Bore Forged Piston Kit +5.00mm","description":"\u003ch3\u003eUnleash Twin-Cylinder Torque with the K8877D500-2 Big Bore Kit\u003c\/h3\u003e\n\u003cp\u003eTransform your Polaris 800cc engine with the professional-grade engineering of the WOSSNER K8877D500-2 Piston Kit. This +5.00mm oversize (85mm bore) forged twin-piston set is specifically designed for the high-torque demands of the Polaris RZR, Ranger, and Sportsman 800. Whether you are rebuilding a tired utility workhorse or a trail-shredding RZR, these pistons provide a substantial strength upgrade over stock cast components. Forged from aerospace-grade aluminum, this kit ensures your parallel-twin engine runs cooler and more reliably during the most intense riding sessions. Available now at Moto-House MX—the leader in high-performance UTV engine solutions.\u003c\/p\u003e\n\n\u003cp\u003eThe technical precision of the K8877D500-2 is built for longevity and efficient power delivery. Featuring advanced radial boss machining and enhanced oiling slots, these pistons ensure the wrist pins stay perfectly lubricated even under high-load conditions. The skirts are treated with a specialized dry-film coating to minimize friction and prevent scuffing, while the ring lands are reinforced for superior oil control and a rock-solid seal. With a precision-engineered 12.0:1 compression ratio, this kit maximizes combustion efficiency while maintaining compatibility with premium fuels. This complete dual-piston set includes everything required for a professional top-end restoration: two forged pistons, high-tension rings, wrist pins, and heavy-duty pin locks.\u003c\/p\u003e\n\n\u003ch3\u003eTop Features: WOSSNER K8877D500-2 Twin Piston Kit\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cb\u003eBalanced Twin-Cylinder Set:\u003c\/b\u003e Includes two matched forged pistons designed specifically for the Polaris 800cc parallel-twin engine.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003e+5.00mm Big Bore (85mm):\u003c\/b\u003e The ultimate solution for rescuing worn cylinder blocks and significantly increasing engine displacement.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eAdvanced Pin Lubrication:\u003c\/b\u003e Radial boss machining and annular grooves optimize oil flow to protect wrist pins during high-stress operation.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eAnti-Friction Skirt Coating:\u003c\/b\u003e Advanced dry-lubricant coating reduces \"piston rock\" and engine noise for a smoother-running machine.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eAerospace Forged Alloy:\u003c\/b\u003e Superior strength-to-weight ratio compared to OEM cast pistons, perfect for heavy-duty UTV and ATV use.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eExpert Pro-Tip\u003c\/h3\u003e\n\u003cp\u003eA +5.00mm overbore is a significant displacement increase. When installing this kit, we strongly recommend a professional cylinder boring and honing service to ensure exact tolerances, and consider a fuel controller to optimize your mapping for the increased air and fuel demand.\u003c\/p\u003e\n\n\u003ch3\u003eFitment List\u003c\/h3\u003e\n\u003ctable border=\"1\" cellpadding=\"8\"\u003e\n    \u003cthead\u003e\n        \u003ctr\u003e\n            \u003cth\u003eYear Range\u003c\/th\u003e\n            \u003cth\u003eVehicle Brand\u003c\/th\u003e\n            \u003cth\u003eVehicle Model \u0026amp; Size\u003c\/th\u003e\n        \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n        \u003ctr\u003e\n\u003ctd\u003e2008-2014\u003c\/td\u003e\n\u003ctd\u003ePolaris\u003c\/td\u003e\n\u003ctd\u003eRZR 800 \/ RZR S \/ RZR 4 \/ EPS (All Models)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003e2009-2014\u003c\/td\u003e\n\u003ctd\u003ePolaris\u003c\/td\u003e\n\u003ctd\u003eRanger 800 EFI \/ Crew \/ HD \/ Mid-Size\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003e2005-2014\u003c\/td\u003e\n\u003ctd\u003ePolaris\u003c\/td\u003e\n\u003ctd\u003eSportsman 800 EFI \/ Big Boss \/ MV \/ Forest\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003e2012-2017\u003c\/td\u003e\n\u003ctd\u003ePolaris\u003c\/td\u003e\n\u003ctd\u003eRanger 6x6 800\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cb\u003eQ: Is this a complete kit for both cylinders?\u003c\/b\u003e\u003cbr\u003e\nA: Yes, the K8877D500-2 is a complete twin-cylinder kit including two pistons and all necessary hardware for a full 800cc rebuild.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: Do I need to bore my cylinders for this kit?\u003c\/b\u003e\u003cbr\u003e\nA: Yes, this is a +5.00mm oversize kit. Your engine block must be bored out to 85.00mm to accommodate these high-performance pistons.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: Can I use standard pump gas with the 12.0:1 compression ratio?\u003c\/b\u003e\u003cbr\u003e\nA: We recommend using high-octane premium pump gas to prevent detonation and ensure the best performance from this high-compression setup.\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eRecommended Pairings:\u003c\/b\u003e Polaris 800 Top-End Gasket Set, High-Performance Main Bearings, and 4-Stroke Synthetic Engine Oil.\u003c\/p\u003e\n\n\u003cp\u003eStop by our local store in Montverde, FL or enjoy lightning-fast shipping across the USA.\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eMoto-House MX – Choice of Champions\u003c\/b\u003e – is located in Clermont\/Montverde, FL. The Best Motocross\/UTV \u0026amp; ATV Shop in Central Florida.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\/\",\n  \"@type\": \"Product\",\n  \"name\": \"WOSSNER K8877D500-2 Piston Kit\",\n  \"image\": \"\",\n  \"description\": \"High-performance +5.00mm (85mm) forged twin-piston kit for Polaris 800cc engines. 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