{"product_id":"gy6-50cc-139qmb-big-bore-kit-with-head-4t-72cc-64mm-valves","title":"GY6 50cc (139QMB) Big Bore Kit with Head 4T (72cc, 64mm Valves)","description":"\u003ch2\u003e72cc Big Bore Upgrade Kit for 50cc 4-Stroke Engines\u003c\/h2\u003e\u003cp\u003eThis 72cc big bore kit is built to raise the output of 50cc 4-stroke engines, with the 139QMB models as the target. It offers a simple route to increasing your engine's displacement at a reasonable cost. Among \u003ca href=\"\/collections\/gy6-50cc-parts\"\u003eGY6 50cc scooter parts\u003c\/a\u003e, it suits riders who want more power without turning their scooter into a race build. Check your valve stem dimensions for compatibility before you buy.\u003c\/p\u003e\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\u003cp\u003eEverything needed for the engine upgrade is included. The package contains a head assembly with 64mm valves, an iron cylinder with a 47mm bore, and a piston fitted with rings. You will also get a wrist pin, circlips, exhaust and intake studs, and base and head gaskets to finish the job.\u003c\/p\u003e\u003ch3\u003eFitting Guidance\u003c\/h3\u003e\u003cp\u003eMeasure your scooter's current valves accurately before starting. This kit is made for engines using 64mm valves. Scooters with 69mm valves need a different kit. Correct fitting is what delivers the intended performance gains without complications. Follow standard procedures when swapping engine components so everything keeps working as it should.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Iron Cylinder\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSize:\u003c\/strong\u003e 72cc\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePosition:\u003c\/strong\u003e Engine Head\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e CSC Go Max with 50cc 139QMB engine (64mm valves)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eFits:\u003c\/p\u003e\u003cul\u003e\u003cli\u003eCSC Go Max (50cc 139QMB engine, 64mm valves)\u003c\/li\u003e\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eHow to select:\u003c\/strong\u003e Take the valve out of your head and measure the full stem length. This kit requires 64mm valves, not 69mm.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003ePlacement:\u003c\/strong\u003e Part #13 on the cylinder crankshaft diagram for the CSC Go Max.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAlternate versions:\u003c\/strong\u003e For the 88cc 52mm kit for 139QMB\/GY6 50 engines, see \u003ca href=\"\/products\/88cc-big-bore-kit-52mm-50cc-139qmb-gy6-50\"\u003e88cc Big Bore Kit (52mm) - 50cc (139QMB) \/ GY6 50\u003c\/a\u003e. For the 81cc 50mm iron kit for upgrading 139QMB 50cc engines to 81cc, see \u003ca href=\"\/products\/gy6-50cc-139qmb-cylinder-kit-4t-81cc-iron-50mm\"\u003eGY6 50cc (139QMB) Cylinder Kit 4T (81cc, Iron, 50mm)\u003c\/a\u003e.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eBrowse further:\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-kits\"\u003eScooter Big Bore \u0026amp; Cylinder Kits\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":51138227929145,"sku":"TT-24995","price":77.98,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0665\/3358\/9049\/files\/big-bore-kit-w-head-4t-72cc-64mm-valves-for-gy6-50cc-139qmb-1.jpg?v=1794372919","url":"https:\/\/www.trendtimes.com\/products\/gy6-50cc-139qmb-big-bore-kit-with-head-4t-72cc-64mm-valves","provider":"Trend Times Toy Stores","version":"1.0","type":"link"}