Re: 49cc china two stroke average speed
O.K., here we go again.
No speed claims unless they are proven with video, or at least a photo of the bike with a GPS. Speedometers, especially the wart mart kind are notoriously inaccurate.
There are so many factors to be considered when talking about "top speed" on these, like was the engine even broken in yet? running optimally? sprocket size? gas to oil ratio?
Anyhow, 23 or so seems like you very accurately measured the speed of a 50cc bicycle engine kit running with a not quite fully broken in engine and so you are good.
Enjoy your bike, it's not SUPPOSED to be "fast".