The piston in mybike were 63mm....+ Stroke high 69,8 mm..= 210 cc...
V=S x h
---> S= [63:2]x[63:2]x3.14 = [31.5]x[31.5] x 3.14= 992.25 x 3.14 = 3115.665
----> h= 57.8 mm + 12 mm = 69.8 mm
----> V = 3115.665 x 69.8 = 217473.417
====> 210 cc
http://img24.imageshack.us/img24/7124/29102009520.jpg