@ Dear Members...................
Everything is safe and unsafe, I you give a knife to little baby or attaraction to a flame for a baby is an example of it. He/she could harm/hurt himself.
So using cng on a triwheeler (Rickshaw) or motor bike is known to people now.
May be you have seen one 14wl capacity cylinder fixed on some bike, which 3 cylinders set fix in Santro.
Kits are already available for 150cc engines.