Cash flow minimum?

[Marcos De la Cruz]

What is an acceptable minimum amount of annual cash flow for a SFR that's free and clear?

[Joe Villeneuve]

None.  The first mistake is the property is free and clear.  
If you achieved this by paying all cash, then you are losing money.  The CF is only playing catchup to the cost to you of the property.  If you paid all cash, you paid full price for the property, and the cash flow, any amount of cash flow, is only playing catchup.