Nope. No 50cc engine will easily go that fast, but its possible. Requires alot of fiddling with the exhaust timing thou, and you loose basicly all low end power.
Get this book, it helps alot: https://www.amazon.com/Two-Stroke-Performance-Tuning-Bell/dp/1859606199
I know theres a pdf around somewhere, but i cba to google-fu it. Your mileage may vary, and i absolutely love my ref literature i have in my shed.
Cant find any specs for a VM14 or VM14SH, but it should get you 1. great mileage and 2. awesome low end power, assuming its re-jetted correctly, or using a adjustable jet.
Your not going to have much top speed though since it will probably be hitting max flow at about 7-8k rpm. (for 50->70cc that is, after all its a 40% normalized volume increase. in reality its much more because of how the bypass-puschback exhaust compression on a 2stroke works, but meh.)
here, have some reading:
http://www.mopedarmy.com/wiki/Carburetor
http://iheartstella.com/resources/manuals/tuning/Graham-Bell-Two-Stroke-Performance-Tuning.pdf (Page 93 and on, esp page 112 which illustrates the carb sizing i mentioned,, but really, this entire PDF is the GO-TO document of 2 stroke theory, setup and tuning. get the book if you dont like on-screen reading
If you want knowledge, theres only ... well technicly two sources ... http://www.amazon.com/Two-Stroke-Performance-Tuning-Bell/dp/1859606199/ AND
http://www.amazon.com/Two-stroke-Tuners-Handbook-Gordon-Jennings/dp/0912656417 (the Graham bell book is better thou, imo, since its 20 years newer...)