{"product_id":"universal-parts-standard-cvt-drive-belt-681-17-7-30-106-92","title":"Universal Parts 681-17.7-30 Belt - 139QMB-B CVT Transmission","description":"\u003ch2\u003e681-17.7-30 Belt\u003c\/h2\u003e\u003cp\u003eRestore the smooth power delivery of your 50cc scooter with the \u003cstrong\u003eUniversal Parts Standard CVT Drive Belt\u003c\/strong\u003e. Specifically sized at 681-17.7-30, this belt is the dedicated replacement for the 139QMB-B engine platform. While standard 50cc belts may slip or cause gear-ratio inconsistencies, this belt is manufactured to the exact width and length specifications required for the \"B-Case\" transmission, ensuring a crisp throttle response and a stable top speed.\u003c\/p\u003e\u003ch3\u003eTechnical Performance Features\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptimized \"B-Case\" Fitment:\u003c\/strong\u003e The 681mm length is specifically tailored for the slightly different pulley spacing found on 139QMB-B engines, preventing the \"slap\" and vibration associated with incorrect belt sizing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurable Composite Construction:\u003c\/strong\u003e Features a high-tensile internal cord structure designed to resist stretching under load, maintaining consistent RPM across your powerband.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e30 ° Performance Groove:\u003c\/strong\u003e Engineered with a precise 30-degree side-wall angle to provide maximum grip against your variator and clutch faces, reducing heat buildup and power loss.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReliable Heat Management:\u003c\/strong\u003e Constructed from a robust rubber compound that maintains flexibility and grip even during long-distance urban commuting.\u003c\/li\u003e\n\u003c\/ul\u003e\u003chr\u003e\u003ch3\u003eComprehensive Fitment Guide\u003c\/h3\u003e\u003cp\u003eThis belt is a primary fit for \u003cstrong\u003e50cc 4-Stroke (139QMB-B)\u003c\/strong\u003e scooters and specific \"B-series\" chassis. Please verify your engine code before ordering:\u003c\/p\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth style=\"text-align: left;\"\u003eEngine Type\u003c\/th\u003e\n\u003cth style=\"text-align: left;\"\u003eCommon Brands\/Models\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e139QMB-B\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eRoketa, TaoTao, and various \"B-Series\" imports\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e49cc \/ 50cc 4-Stroke\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eSpecific models requiring the 681mm length profile\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eB-Case Transmission\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eGeneric Chinese \"Street Legal\" 50cc scooters\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003chr\u003e\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLength:\u003c\/strong\u003e 681mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTop Width:\u003c\/strong\u003e 17.7mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGroove Angle:\u003c\/strong\u003e 30 °\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Code:\u003c\/strong\u003e 139QMB-B \/ QMB139-B\u003c\/li\u003e\n\u003c\/ul\u003e\u003chr\u003e\u003cblockquote\u003e\n\u003cstrong\u003eMechanic's Note:\u003c\/strong\u003e The \"B\" in 139QMB-B signifies a specific transmission variation. Using a standard 669 or 729 belt on this engine will result in poor acceleration or belt failure. \u003cstrong\u003ePro Tip:\u003c\/strong\u003e Check your \u003cstrong\u003e\u003ca href=\"https:\/\/www.scooterworks.com\"\u003eCVT Air Filter\u003c\/a\u003e\u003c\/strong\u003e when you replace this belt; a clogged filter causes the belt to run hot, leading to the glazing and snapping you're trying to avoid!\u003c\/blockquote\u003e\u003cp style=\"font-size: 0.85em; color: #666;\"\u003e\u003cstrong\u003eSKU:\u003c\/strong\u003e 106-92 \u003cbr\u003e\u003cstrong\u003eMPN:\u003c\/strong\u003e 3059 \u003cbr\u003e\u003cstrong\u003eVendor:\u003c\/strong\u003e Universal Parts\u003c\/p\u003e","brand":"Universal Parts","offers":[{"title":"Default Title","offer_id":49986069627160,"sku":"106-92","price":19.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0782\/1728\/1816\/files\/106-92.webp?v=1747253973","url":"https:\/\/www.scooterworks.com\/products\/universal-parts-standard-cvt-drive-belt-681-17-7-30-106-92","provider":"Scooterworks USA, LLC","version":"1.0","type":"link"}