From what I have been told the NS400r pistons are unavailable now even from Honda.

So good luck with the search maybe worth having a chat with Jamie ( http://www.dreamgate.ne.jp/nsr/index.html ) as he is out in Japan and maybe able to put you in touch with some one he can source you some pistons.

BOSOZOKU
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MC21R Repsol replica
SC36 'Fire storm'
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