Iron or aluminum alloy? If it weighs 14 Kg or more, it's most likely steel frame. Put your fingers on the junction box while sit on and off the saddle, you should not feel any movement at all at the joint. Many junction box are not precision cast/machined, that's the problem.
Your bike looks similar to Irland Camaro (divide by 30 to get US$ value)
http://goods.ruten.com.tw/item/show?21101171853628