You will useally have more choices on the rear due to space limitations. That way you have a wider range of ratois to choose from. If they have a 1 tooth larger front it will slow down your top end , and increase your take off but not by much at either end. It is a start though. Try it and see if it is enough. Three down at the rear will add to that alot. maybe both together will give the wheelie popin forth gear. By ID i mean the Inside Diameter of the hole in the sprocket, and notches are the teeth inside that hold the position on the output shaft. Your front sprocket sounds like it is simply bolted on with no notches so you may be able to buy a sprocket that fits the shaft, and have the mounting holes drilled. If so Use Grade 8 bolts/ lock washers, and blue lock tight on the bolts. Of course I am jumping ahead a few steps, but the mods always start somewhere! Keep posting because someone else may be looking at the same situation you are. Billions of people/ millions of scooters/ couple dozen forums