Fastest BL motor on 6 or 7 cells?

okay, I just went out and test drove it. I geared up to 18/81. I know that was a little extreme, but it's cool out so I figured I give it a try.

First I want to say that I am really liking the 8S motor. It's got all the power I need. I think my problem is this MGM controller.

Right off the bat not even 10 seconds into it the trucks starts cutting off. I hear two beats and it comes back on. Sometimes it's one beat and I'm ready to go. I didn't even have a chance to get it warm. It just kept cutting off.

Does anyone know what is happenining. I thought I got the programing correct. Now I am rethinking it. Any help would be greatly appreciated.