Transferring Old IRA funds to New Solo 401K ?

[Tricia O'Brien]

If I set up a Solo 401K now, can I transfer IRA assets from an old IRA I established 2 years ago into the new 401K? I'm referring to an old IRA that holds stock mutual fund (say a Janus Fund). Or is the Solo 401K only to be funded from money I earn from self employment after the 401K is established ? Any replies would be appreciated!