Would a bad cdi coil stop my dt 125 revving properly as it gets to about 6-7k and seems to bog and no more power

Could do, but nine times out of ten this sort of problem is fuel related in my experience. We do get the odd coil that breaks down at high RPM but its rare these days.

I think it might be the float sticking how do I adjust the float or check if it is the float causing the problem

Got a Haynes book of myths? They usually have pictures and diagrams to help with this.