If your thinking about rebuilding your CRF50 or XR70 or even your Lifan 50, 70 or 90, this is a great price for basically a new engine. Stroker kit comes with a new stroker crank (94.5mm), 47mm piston, rings, pin, clips, cylinder, longer studs and a longer timing chain. Gasket set and a head with intake and exhaust valves. An XR70 cam, springs and rockers will work. You can purchase a big bore kit to increase the displacement to 117cc. A stroker motor pulls harder than just a big bore kit. free shipping. I am throwing in a cam and a very lightly if at all used sprocket.