Andy wrote:The MC16 F-III uses 28mm carbs, and in "standard" HRC form (i.e. all the HRC bits bolted together but unmodified) is rated at 68hp!

As you say Andy, the MC16 F3 uses 28mm carbs...........

I don't believe this is an F3.

If anyone's fitted bigger carbs to the stock 16 it would be a good time to let us know how it went.