On the block you will find a number cast mine is on the left side under the transmission. This is on the block generally you can find a casting on the head as well but sometimes they miss with that before they ship the bikes.......
if the casting says:
1p39fmb = 49cc
1p47fmf = 70cc
1p47fmf = 90cc
1p50fmg = 100cc
1p52fmh = 110cc
hope this helps
if the casting says:
1p39fmb = 49cc
1p47fmf = 70cc
1p47fmf = 90cc
1p50fmg = 100cc
1p52fmh = 110cc
hope this helps