Kymcos are speed limited by means of the ignition system which sets the maximum rpm. Most models are unlocked by changing the CDI (not expensive). The key to doing this is to find out which after-market Chinese CDI isn't rpm limited. Kymco is NOT helpful, and the dealers likewise are not helpful. The Chinese CDI makers are likewise not helpful. Many CDIs are interchangeable from one model to the next, and there's no harm in buying aftermarket CDIs and trying them out. For example, 50cc CDIs and 150cc CDIs are interchangeable. You must, however, figure out if your unit is an AC-type CDI unit or a DC-type. It's worth trying to figure this since the performance gains are huge. Here's a few sample CDIs from 50-150cc Kymcos: