I can purchase small reversible motors of differing speeds. What speed in rpm is a good speed for furling?
My motor runs at 6000rpm. I think Jack Hise furls a little faster than that. It really is up to the individual and what he/she can handle.
Brad
i follow the Kathy Scott rule: about a 10% reduction in length when furling each leg. This makes the rpm factor less relevant. I’ve even seen some use a hand drill mounted with a cup hook.
Agreed, but the original question was about motor speed, not percent of reduction. Jack uses a Dremel with a cup hook and does a 10%reduction, one leg at a time. My machine furls both legs at once and my reduction is somewhere in the 12% range. I have tried more reduction, but the leaders are just too stiff and unruly. The bottom line is make a few, give them a test and decide if what you made will work for you. If not change something and try again until you make something that works for YOU!
Brad
Thank you Kaboom. exackery what I wanted to know.
Mike here from Streamside Furled Leaders Here.
I make about 8,000 leaders / tenkara lines a year.
My motor runs at 20,000 rpm but has a variable speed control like the pedal on a sewing machine. I don’t think I have ever had it over 5,000-6,000 rpm while furling. I have had it almost wide open when re-spooling bobbins. 
The furler that Michael Hackney made for me has a gear ratio of 1 to 1. I like the added control it gives me.
I use a variable speed motor salvaged from a thrift store sewing machine. I comes with a foot pedal speed control and 1/4 horse power A/C motor. I have no idea what the final RPM is for my pulley driven winding head, but I can get it to just barely turn or spin way faster than I need.
I think I paid less than $20 for the old sewing machine, they are full of parts useful to the hobbyist. High quality motor, gears, bearings, collar shafts and a very nice thread tension system that now lives on my rod wrapping jig.