{"product_id":"cvk-main-jet-138-for-scooters-mopeds","title":"Cvk Main Jet (# 138) for Scooters \u0026 Mopeds","description":"\u003ch2\u003eCvk Main Jet (#138) for 139QMB and GY6 Scooters\u003c\/h2\u003e\u003cp\u003eThe Cvk Main Jet (#138) is a precision component designed for scooters and mopeds equipped with 139QMB and GY6 engines. This replacement part is important for ensuring proper fuel delivery and improving engine performance. It is one of the \u003ca href=\"\/collections\/scooter-carburetors\"\u003escooter carburetors \u0026amp; jets\u003c\/a\u003e that play a significant role in the bike's operation. The main jet is compatible with various CVK carburetors that accept a 5mm main jet.\u003c\/p\u003e\u003ch3\u003eJet Specifications\u003c\/h3\u003e\u003cp\u003eThis main jet features a Keihin round-style design, known for its reliability in performance applications. With a thread size of M5x0.80 and an overall length of 8mm, it fits within the designated carburetor slot. Adjusting the jetting may require some trial and error to achieve the best performance for your specific setup.\u003c\/p\u003e\u003ch3\u003eWhen to Replace Your Main Jet\u003c\/h3\u003e\u003cp\u003eReplace your main jet if you notice poor throttle response, inconsistent idle, or if you have made modifications to your engine that may affect fuel flow. Regular maintenance and appropriate jetting can help keep your scooter running smoothly and efficiently.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Main Jet\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Size:\u003c\/strong\u003e M5x0.80\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOverall Length:\u003c\/strong\u003e 8mm\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eThis main jet is suitable for 139QMB-based 50cc \/ 80cc engines and 157QMJ-based 125cc \/ 150cc \/ 169cc engines. If your engine code contains \"QM\" or \"FM\" and you are using a CVK carburetor that accommodates a 5mm main jet, it will likely be compatible.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e139QMB\u003c\/li\u003e\n\u003cli\u003eGY6\u003c\/li\u003e\n\u003cli\u003e157QMJ\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eNot sure it fits? Contact us with your scooter's make, model and year and we'll confirm the fit before you order.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eShop more:\u003c\/strong\u003e \u003ca href=\"\/collections\/scooter-carburetors\"\u003eScooter Carburetors \u0026amp; Jets\u003c\/a\u003e · \u003ca href=\"\/collections\/scooter-parts\"\u003eScooter Parts\u003c\/a\u003e\u003c\/p\u003e","brand":"Magic Cars","offers":[{"title":"Default Title","offer_id":52800353173735,"sku":"25-914490","price":3.6,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/2245\/9711\/files\/cvk-main-jet-138-1.jpg?v=1791665692","url":"https:\/\/www.magiccars.com\/products\/cvk-main-jet-138-for-scooters-mopeds","provider":"MagicCars","version":"1.0","type":"link"}