http://www.tradekey.com/product_view/id/1114775.htm
It's interesting that they advertise that bike for sale on the tradekey B2B site.
http://751248727.en.ec21.com/company_info.jsp
Those are more advanced engines....that v-twin also has a very powerful 125cc half version of it. A 125cc DOHC 4-valve that has a very good hp rating. The twin offers about 30hp and the single about 15hp.
Here is a Yin Xiang 233cc that has four valves?
20hp @ 8000 rpm