Its all in your hips. Once you come around to 7, dont open up to slow your rotation, and just swivel them hips the extra 90 that you need
the size of the jump makes the biggest difference when you are trying bigger spins. if you are going for a nine then make sure you are hitting a jump of 30ish feet and over. It also helps if you learn how to grab and really just get a grip on how to conrol your spins well.