{"product_id":"wossner-8134d150-piston-kit-yamaha-yz250-wr250-1988-1991-1-50mm-oversize","title":"Wossner 8134D150 Piston Kit - Yamaha YZ250 WR250 1988-1991 +1.50mm Oversize","description":"\u003ch3\u003eWossner 8134D150 Standard Series Forged 2-Stroke Piston Kit - +1.50mm Oversize\u003c\/h3\u003e\n\n\u003cp\u003eGive your vintage Yamaha YZ or WR a second chance with the Wossner 8134D150 Piston Kit. Specifically designed for the 1988-1991 Yamaha YZ250 and the 1991 WR250, this +1.50mm oversize forged kit is the professional solution for cylinders that require significant boring to remove deep scoring or wear. At Moto-House MX, we specialize in keeping legendary 2-strokes on the track; Wossner’s aerospace-grade forging provides a massive durability upgrade over traditional cast pistons, ensuring your 250cc engine can handle the heat and pressure of modern riding.\u003c\/p\u003e\n\n\u003cp\u003eThe 8134D150 features a dual-ring configuration, which is ideal for the broad powerbands of late 80s and early 90s Yamahas. This design provides superior heat dissipation and a long-lasting compression seal, helping your engine maintain consistent power throughout the moto. To ensure smooth operation and reduced engine noise, Wossner applies a permanent molybdenum disulphide skirt coating that minimizes friction and protects the cylinder wall. Precision-machined for a 69.50mm finished bore, this 69.44mm piston kit restores your Yamaha to peak mechanical performance.\u003c\/p\u003e\n\n\u003ch3\u003eTop Features: Wossner 8134D150 Piston Kit\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cb\u003e+1.50mm Oversize (69.44mm):\u003c\/b\u003e The perfect choice for cylinders that need to be bored out to remove deep scratches, resulting in a fresh 69.50mm bore size.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eDual Ring Configuration:\u003c\/b\u003e Offers enhanced cooling and a reliable compression seal, maintaining power in both motocross and off-road environments.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eAerospace-Grade Forging:\u003c\/b\u003e Engineered to be significantly stronger and more heat-resistant than original cast equipment.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eLow-Friction Skirt Coating:\u003c\/b\u003e Permanent skirt treatment reduces internal drag and protects the cylinder wall for a quieter engine and smoother break-in.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eOptimized Machining:\u003c\/b\u003e Precisely balanced to reduce reciprocating weight while maintaining maximum strength in the crown and skirt walls.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eComplete Kit:\u003c\/b\u003e Includes the high-performance forged oversize piston, rings, wrist pin, and circlips.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cb\u003eExpert Pro-Tip:\u003c\/b\u003e When moving to a +1.50mm oversize, it is critical that your cylinder is precision-bored and honed by a qualified machine shop to exactly 69.50mm. This ensures the correct piston-to-wall clearance for a forged assembly. For a professional-grade rebuild, always install with a fresh top-end gasket kit and use high-quality 2-stroke premix oil to protect your new forged piston during the initial heat cycles.\u003c\/p\u003e\n\n\u003ch3\u003eFitment List\u003c\/h3\u003e\n\u003ctable border=\"1\" cellpadding=\"8\" style=\"width: 100%; border-collapse: collapse;\"\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\u003c\/th\u003e\n        \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n        \u003ctr\u003e\n\u003ctd\u003e1988-1991\u003c\/td\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYZ250\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003e1991\u003c\/td\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eWR250\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: Why use an oversize piston instead of a new cylinder?\u003c\/b\u003e\u003cbr\u003e\nA: Boring your existing cylinder to a +1.50mm oversize is a cost-effective way to restore factory performance. It removes damage while allowing you to keep the original cylinder casting, which is often higher quality than aftermarket replacements.\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eQ: Is a forged piston better for my 1990 YZ250?\u003c\/b\u003e\u003cbr\u003e\nA: Yes. Forged pistons are much more resilient to the heat and stress of high-performance 2-strokes. They offer a higher level of structural integrity, which is essential for engines that are 30+ years old.\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eQ: Does this kit include the wrist pin bearing?\u003c\/b\u003e\u003cbr\u003e\nA: This kit includes the forged piston, dual rings, wrist pin, and circlips. The small-end needle bearing is sold separately. We always recommend installing a new bearing with every top-end rebuild.\u003c\/p\u003e\n\n\u003ch3\u003eRecommended Pairings\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cb\u003eComplete Top End Gasket Set:\u003c\/b\u003e Vital for a leak-free seal and proper engine cooling.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003ePremium 2-Stroke Premix Oil:\u003c\/b\u003e Ensure your new oversize forged piston is protected from the very first start.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eRestore your machine’s power and precision today. Buy now at Moto-House MX!\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. Stop by our local store in Montverde, FL or enjoy lightning-fast shipping across the USA.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\/\",\n  \"@type\": \"Product\",\n  \"name\": \"Wossner 8134D150 Piston Kit\",\n  \"image\": [],\n  \"description\": \"Premium Wossner 8134D150 Forged 2-Stroke Dual Ring Piston Kit for Yamaha YZ250 and WR250 (1988-1991). +1.50mm Oversize (69.44mm) for 69.50mm bore.\",\n  \"sku\": \"8134D150\",\n  \"brand\": {\n    \"@type\": \"Brand\",\n    \"name\": \"Wossner\"\n  },\n  \"offers\": {\n    \"@type\": \"Offer\",\n    \"url\": \"https:\/\/motohousemx.com\/products\/wossner-8134d150-piston-kit\",\n    \"priceCurrency\": \"USD\",\n    \"availability\": \"https:\/\/schema.org\/InStock\"\n  }\n}\n\u003c\/script\u003e","brand":"WOSSNER","offers":[{"title":"Default Title","offer_id":44495992389715,"sku":"8134D150","price":182.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1754\/5421\/files\/480433.png?v=1776229638","url":"https:\/\/motohousemx.com\/products\/wossner-8134d150-piston-kit-yamaha-yz250-wr250-1988-1991-1-50mm-oversize","provider":"Moto-House MX","version":"1.0","type":"link"}