{"product_id":"brc-510cc-conversion-kit-yamaha-yz-250-1999-2025","title":"Brc 510cc Conversion Kit Yamaha YZ 250 1999-2025","description":"\u003cp\u003eThis BRC 510cc conversion kit is a bolt-in two-stroke engine conversion for Yamaha YZ250-based applications from 1999 to 2025, intended to build a larger-capacity counterbalanced engine by reusing selected parts from a donor YZ250 engine. In practical terms, it allows the original YZ250 platform to be rebuilt into a motocross-focused engine package with stronger output and smoother delivery, rather than relying on a complete replacement engine assembly.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFeatures\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBolt-in conversion based on the Yamaha YZ250 platform\u003c\/li\u003e\n\u003cli\u003eDeveloped as a 500cc-class counterbalanced two-stroke conversion\u003c\/li\u003e\n\u003cli\u003eMotocross-focused power delivery\u003c\/li\u003e\n\u003cli\u003ePneumatic power valve system for smooth, linear response\u003c\/li\u003e\n\u003cli\u003eTriple-blade power valve arrangement for stronger bottom-end response\u003c\/li\u003e\n\u003cli\u003eKick-start compatible\u003c\/li\u003e\n\u003cli\u003eFitted decompression button to assist starting\u003c\/li\u003e\n\u003cli\u003eIntegral counterbalance shaft to reduce vibration\u003c\/li\u003e\n\u003cli\u003eSupplied with a purpose-built exhaust pipe and silencer\u003c\/li\u003e\n\u003cli\u003eIntended to run with the stock carburettor\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eDonor Components Required\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eRequires components from a donor Yamaha YZ250 engine from the listed applications\u003c\/li\u003e\n\u003cli\u003eReuses original engine parts to build the 510cc engine\u003c\/li\u003e\n\u003cli\u003eAccepts donor Yamaha YZ250 and YZ250X transmission components\u003c\/li\u003e\n\u003cli\u003eDonor engine parts used in the build include the clutch assembly, kicker assembly, water pump, intake, ignition and covers where possible\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eSpecifications\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eOutput: 60+ hp\u003c\/li\u003e\n\u003cli\u003eTorque: 50+ ft-lb\u003c\/li\u003e\n\u003cli\u003eBore: 89 mm\u003c\/li\u003e\n\u003cli\u003eStroke: 80 mm\u003c\/li\u003e\n\u003cli\u003eCompression ratio: 12.8:1\u003c\/li\u003e\n\u003cli\u003eTransmission oil capacity: 1100 cc\u003c\/li\u003e\n\u003cli\u003eFuel requirement: minimum 91-octane petrol\u003c\/li\u003e\n\u003cli\u003ePremix ratio: 50:1\u003c\/li\u003e\n\u003cli\u003ePremix ratio for snowbike and desert use: 32:1\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCross-Reference OEM Part Numbers\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eNeutral switch block-off kit: 08-05-012\u003c\/li\u003e\n\u003cli\u003eService piston: Vertex 22447\u003c\/li\u003e\n\u003cli\u003eConnecting rod: ProX 03.1406\u003c\/li\u003e\n\u003cli\u003eConnecting rod: Wossner P2044\u003c\/li\u003e\n\u003cli\u003eLeft-side transmission output shaft cylindrical roller bearing: NJ205EC3\u003c\/li\u003e\n\u003cli\u003eEquivalent replacement bearing: KTM 49030023000\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eInstallation Notes\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBoth lower radiator fitting locations must be relocated using the supplied 6061-T6 caps and fittings\u003c\/li\u003e\n\u003cli\u003eThe donor YZ250 cylinder-head hose must be shortened to suit the taller cylinder\u003c\/li\u003e\n\u003cli\u003e2010 and older donor YZ250 engines require a neutral switch block-off kit\u003c\/li\u003e\n\u003cli\u003eUses readily available consumables including KTM-sourced bearings and seals, and gaskets made by Cometic\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eVehicle Fitments\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eYamaha YZ250, 2005-2025, aluminium frame models, fits without fabrication\u003c\/li\u003e\n\u003cli\u003eYamaha YZ250, 1999-2004, steel frame models, minor modification required\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Unbranded","offers":[{"title":"Default Title","offer_id":57509515329916,"sku":"BRC-YZM500_99-21","price":0.0,"currency_code":"GBP","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0666\/3952\/8167\/files\/brcyzm500.jpg?v=1790565747","url":"https:\/\/radhouse.co.uk\/products\/brc-510cc-conversion-kit-yamaha-yz-250-1999-2025","provider":"Radhouse","version":"1.0","type":"link"}