think you missed this little disclaimer on the parts manual
*NOTE: Part numbers are reproduced from the official 1987~1994 Honda Parts Manuals, and therefore subject to updates.
Consequently, this online version is for reference only, and all part numbers should be cross-referenced with an official Honda dealer.
and as for the part number being incorrect? I just checked my actual parts manual that covers all model year MC21's and that's the part # for item 10 (the 68mm snap ring). It lists needing 1 for the rebuild.
I think you were looking for item #11.
94601-15000 Clip Piston pin 15MM . You need four of those.
As for the image being wrong? Nope, that's the correct image for the MC21 (F 2). Are you sure you looked a the correct year/model? You may have been looking at the 1988-1989 (MC18). MC21 1990-1993 has the correct images, as well as part numbers per the actual manual.
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Charles Gallant