I have searched several sites that show open air current capacity and bundled wire capacity, like here
http://www.powerstream.com/Wire_Size.htm
For 18g I can multipy 2.3A * 1.7 to get 4A. This is very conservative. What current have you all been running up to without being concerned for a burn-out?
I have to post pictures, but my stator is cast in resin/glass/marble dust, and the center of each coil is open.