{"product_id":"gy6-50cc-139qmb-performance-cylinder-head-81cc-50mm","title":"GY6 50cc (139QMB) Performance Cylinder Head 81cc 50mm","description":"\u003ch2\u003eAluminum Performance Cylinder Head for GY6 50cc Engines\u003c\/h2\u003e\u003cp\u003eThis 81cc aluminum performance cylinder head is built for 50cc engines based on the 139QMB model. It suits riders who want more output from their scooter, particularly in city traffic and on hills. It is one of the \u003ca href=\"\/collections\/gy6-50cc-parts\"\u003eGY6 50cc scooter parts\u003c\/a\u003e that can deliver a noticeable power gain when matched with an 81cc cylinder kit.\u003c\/p\u003e\u003ch3\u003eBuild and Fit Details\u003c\/h3\u003e\u003cp\u003eThe head is cast from aluminum, which helps it last and manage heat well. Its 50mm stud spacing lets it bolt directly onto several QMB\/QMA engine families. A 64mm rocker arm assembly is needed to run it, and that assembly is sold separately. Both the intake and exhaust ports use 6mm threads.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Aluminum\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStud Spacing:\u003c\/strong\u003e 50mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHead Height:\u003c\/strong\u003e 60mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntake Port:\u003c\/strong\u003e 24mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExhaust Port:\u003c\/strong\u003e 22mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntake Valve:\u003c\/strong\u003e 21.5 x 64mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExhaust Valve:\u003c\/strong\u003e 19 x 64mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eValve Stem Diameter:\u003c\/strong\u003e 5mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eValve Stem Length:\u003c\/strong\u003e 64mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntake Threads:\u003c\/strong\u003e 6mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExhaust Threads:\u003c\/strong\u003e 6mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHead Height w\/ Intake Valves:\u003c\/strong\u003e 66.1–67.3mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e CSC Go Max (139QMB \/ GY6 50cc engine, 64mm valve stems)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eCompatible with:\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eCSC Go Max\u003c\/li\u003e\n\u003cli\u003eOther GY6 50cc (139QMB) scooters\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eChoosing the right part:\u003c\/strong\u003e Check your stock valve stem height first. This head requires 64mm valves and a 64mm rocker arm, whereas most stock 139QMB heads use 69mm.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003ePlacement:\u003c\/strong\u003e Refer to part #4 on the CSC Go Max cylinder head camshaft diagram.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eOther option:\u003c\/strong\u003e \u003ca href=\"\/products\/cylinder-head-valve-assembly-for-csc-go-gy6-50cc-139qmb-scooters\"\u003eCylinder Head \u0026amp; Valve Assembly for CSC Go., GY6 50cc (139QMB) Scooters\u003c\/a\u003e (CSC Go. 139QMB scooters, Cylinder Head \u0026amp; Valve Assembly).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eBrowse more:\u003c\/strong\u003e \u003ca href=\"\/collections\/gy6-50cc-parts\"\u003eGY6 50cc Scooter Parts (139QMB)\u003c\/a\u003e · \u003ca href=\"\/collections\/gy6-scooter-parts\"\u003eGY6 Scooter Parts\u003c\/a\u003e · \u003ca href=\"\/collections\/scooter-cylinder-heads\"\u003eScooter Cylinder Heads \u0026amp; Valves\u003c\/a\u003e · \u003ca href=\"\/collections\/scooter-parts\"\u003eScooter Parts\u003c\/a\u003e\u003c\/p\u003e","brand":"Trend Times Toy Stores","offers":[{"title":"Default Title","offer_id":51138795798585,"sku":"TT-26788","price":164.98,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0665\/3358\/9049\/files\/gy6-50cc-139qmb-performance-cylinder-head-81cc-50mm-1.jpg?v=1794377849","url":"https:\/\/www.trendtimes.com\/products\/gy6-50cc-139qmb-performance-cylinder-head-81cc-50mm","provider":"Trend Times Toy Stores","version":"1.0","type":"link"}