Kickturn with front trucks over the coping, but bailing when I pump higher 

In this session I'm trying to kickturn with the front trucks over the coping, as some kind of step towards slash grinds. I focus on turning my back shoulder forward/frontside during the approach which feels great and gives me more confidence. To do the actual kickturn I'm using Mitchie at SkatieIQ's technique of "hitting my hip" with my back elbow to "quick start" the rotation and then just wait for the rotation to complete. That also feels great.
I don't know why I'm bailing when I pump harder. Is it just fear and bad habits, or is it something else? My approach and the quick start of the kickturn looks very similar in the almost vs bail case.