Why can't Naruto transform into the Nine Tails? Killer B is able to transform into the 8 tails at will and be in control as he befriended the 8 tails.

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Naruto has befriended the 9 tails too, but we never saw him transform into the Nine Tails like he did when he was fighting Pain and lost control of the Nine Tails (made of bones and muscles).

 

Now all we get to see him transform into is a kind of Susanoo like Nine Tails cloak.

 

Why doesn't he transform into the actual Nine Tails(made of flesh and bones like in picture below)?
I do not know for sure, but I think Kurama cannot appear in that statue because Naruto has half of his power. If we retrieve when Minato sealed the Kyuubi (on the early incident of the masked man, Obito), Minato sealed the Kyuubi twice: once in himself and another in Naruto.