Radiator Problem

[Terrytt]

Hi,
Can anyone help me with this - I fitted a new radiator to my motorbike and the fluid seems to be pouring out of this little L shaped thing on the side. I'd assumed that it would be some type of bleeding device, but it seems to be functioning as a hole at the moment.
I've enclosed a picture. The thing I'm talking about has blue antifreeze leaking out.
I'm looking for some suggestions about how to fill up my coolant system.
Thanks

[Terrytt]

Hi Ryan,
no it wasn't on the old radiator, and it didn't have any other pipes connected to it.

[Terrytt]

I'm just a bit puzzled as to why this is fitted - surely it must have some purpose. It's definately the right radiator - it's taken me about 10 hours to fit (mods needed) so I'm not keen to change!!.
Thanks