You haven't save enough? What do you mean by that? If you are looking for help you'd be better off over killing your point, so everyone understands, than saying less..

But how can you do so many pull ups in a row? Have you been lifting before, and also how are you doing these? When my form starts to break, I resort back to my form and try to get one more last rep, then do whatever it takes to get up there (which is what I imagine gets you 40) and then hold it until I slowly lose it to the ground.

Proper form, in my humble opinion, is not moving or twisting or bring legs up, but being perfectly still. Also, I don't count it unless my head is above the bar completely.