Check the listing for details. Rear Hub Adapter 1.25" and Multifunctional 40T Sprocket - 2 Stroke Engine Kit. Condition: New. Listed at 49.66 USD. 1. This 1.25 inch adapter can be used for our 3+6+9 hole multifunctional sprocket and also compatible with our 44/40 teeth 3 holes high performance sprocket 2. Do not works with 9 hole and 6 hole sprocket. Key Product Features The Adapter fits 1.25 inch rear hub of SPOKE WHEEL BIKE with a diameter of 1.21"to 1.25" (FOR SPOKE WHEEL BIKE ONLY)Does not works with 9 hole and 6 hole sprocket, Only fit spoke wheel bicycle;2pcs screw 12.9 Grade/W3/8-16X1" , 3pcs screw 10.9 Grade/W5/16-18X1";Adapter is a durable aluminum unit fully cnc machine made that provides fast and easy installation;Worked well on gas motor kit 48cc/50cc/66cc/80cc gas motorized bicycle;please note: The bigger three allen bolts diameter is 10mm; 40T Sprocket Key Product Features - Thickness:4cm; Length:16.5cm, Diameter of center hole:37mm - Compatible with stocked installation kit 9 hole set; - Compatible with 1.5 inch adapter of bike rear hub; Compatible with 1 inch adapter of bike rear hub ; - Compatible with spoke wheel and mag wheel which are designed for motorized bicycle; - Package: 1pc 40 teeth sprocket only; Excluding boltsFor spoke wheel only.2pcs screw 12.9 Grade/W3/8-16X1"3pcs screw 10.9Grade/W5/16-18X1"Inner diameter size is around 31.5mm;The Adapter fits 1.25 inch rear hub of SPOKE WHEEL BIKE with a diameter of 1.21"to 1.25" ;Screw to screw center distance is about 78mm;CNC Fully Made 1.25 inch hub adapter.Works well with our multifunctional 3/6/9 holes sprocket.Clients DIY for your reference: Thank you so much for views, We truly care much more your purchasing experience,We are 100% dedicated to your complete satisfaction. if you have any questions,please freely to ask and I will do my best to get back to you promptly!Products usually shipped on the second business day and you will receive message of tracking id.DONSP1986 is registered officially in year 2012 and started business in year 2008, we can provide engine kits, high performance spare parts of engine, motorized bicycle and spare parts of bike. hope you can have a great time when shopping with us.