It is quite a challenge to be sure an SP is genuine as parts are interchangeable. It depends on what your outcome is really. If you want a nice Rothmans NSR with all the correct parts it wouldn't matter to me as long as they are all there, as I would want it to look good, make the right noises and ride well. If it's an investment that's a different matter. There are some on ebay that look like the right spec, but they might need a complete refresh, like this one https://www.ebay.co.uk/itm/Honda-NSR250-R-SP-MC21-1992-26k-miles/152927591417?hash=item239b31dbf9:g:dnkAAOSws-ta~F-z
By the sound of that bike on their video, it probably needs an engine refresh as well! Quite a few kicks to get it going and then sounded like it wasn't running on both cylinders
If it needs a repaint then it's quite a challenge to get OEM decals, although copy decals are available or some good painters can recreate them. There are some excellant restorers like JonMac who could possibly be persuaded undertake a refresh for you
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