hi ian

officially the TEU-101BK has a 27 turn limit as it is designed to work with the sport tuned motor
lots pf people have run it with lower turn motors but its a bit of a gamble run the risk of overheating

try a stock 27t orion racing motor
you maybe ok with 25 turn motors
and maybe even a 23 but that is really pushing it If you are willing to run the risk
hope that helps