We don't necessarily all agree that it runs too lean. The one and only person that I have talked to directly that has run a standard three wheeler on a dyno was adamant that it did not run lean.
As an aside, much of the perceived wisdom regarding "correct" spark plug colour is of dubious worth. Unleaded fuel burns cleaner than leaded ever did so with correct fuel mixture plugs always look much whiter than the classic biscuit colour. Much better to carry out a full on plug chop then assess the colour of the piston crown deposits. Not terribly practical in the real world and few people will manage a proper plug chop anyway. Better to go by exhaust gas analysis on the rolling road followed by tweaking of mapping on the real road if necessary.
