The 173FMM its a 249cc oil cooled single Lifan is manufacturing.

http://item.taobao.com/item.htm?id=13057532723

It also is a six speed, rated @ about 20hp 8000rpm

Here is a thread on it at Motofans China.
http://www.motorfans.com.cn/bbs/t_16978371.htm

Most want to know where they can purchase the enginein an actual motorcycle.
Others allude to it being a copy of the Suzuki GS250? Other think its a copy of a Yamaha 250?

It cries for somebody to take one and build a bike around it.It is the engine proposed for the Cossack, the dirt bike Lifan has been exhibiting, but they have some notion that they can use the frame to circulate and cool the oil.

http://www.mychinamoto.com/forums/sh...IFAN-LF250GY-2