Start with a 1/16. Mine is at 3/32 and could go even a bit larger. The regulator is in a bit and I have the perfect motor now (although it is getting old and tired and has just about zero compression when cold, it runs like a top and yanks the CGM Ultimate around like a yo-yo).

Other things to consider.

1. It started to run awesomely after the third or fourth gallon.

2. It thrives on Coolpower 30% heli

Mark