I was able to order individual Keihin jets from my local honda shop - in fact, they had some in stock. My suggestion would be to bring in the stocker from the bike so they see what type it is. Can also look here for part numbers of individual jets (http://www.sudco.com/keihinjets.html). Cost approx. $3 per.

FWIW, if you are running stock (unmodified) airbox, stock motor and injection, with Tyga pipes, I think 165s will be way rich. My experience with MC21 with that exact set-up (but including M-Max de-restricted) was that 145 was too rich (bogged at 10k). Took it to 2-stroke race expert and he dynoed etc. and came up with 122 mains (!) and slightly richer pilot jets. Bike ran well but I was too nervous about it and in the end put 128s (stockers) back. Still runs well, and I may go up to 132s when I have a chance, though it made it through the cold (for San Diego) season without issue. Just some data for reference. hth.
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-Jim
'93 MC21