Most Chinese bikes are like building your own PC...open source manufacturing. Not all companies use Honda based engines. Some use Suzuki and there are a few Yamaha's out there as well. Honda derived engines are by far the most popular so that's why you see so many of them in different frames.

Internally they all may be the exact same but important differences will be in the individual manufactures quality control during the production process. A small hole drilled a little of center or not perfectly straight can cause major problems after 4,000 miles of high RPM riding. Quality control is what you're basically paying for...that and better quality materials (even though the original design may be perfectly identical).

CC