66 cc / 80cc chinese engine motorized bike 26" wheel front and back female japan bike all parts of the engine are stock the above are my specs of my motorized bike. Can someone give an advice on how to higher the bottom end torque of my bike in the cheapest way? the issue here is whenever I pass a hump, I need to gain speed first by pedaling before pulling the throttle or the engine'll die. I am eyeing on changing the wheel size and no. of tooth of sprocket in the engine side.