Been there done those mods! KLX needle uses to much fuel as you already know!
If you have not done the O ring mod how can you be quoting Shakespeare as proof it does not help? If you lose your dreams you are surrendering to failure i refuse to do that, if you have maybe some seat time and wind therapy might be the cure.
Then . . . perhaps, by inspection (examination of the concepts and precepts) only, I'm being too hasty! Jumping to unwarranted conclusions! Please forgive my skepticism and (harder to do) any cynicism. (Just for the record, I quoted fictional detective Sam Spade, not Shakespeare.)
Maybe, after 30 plus years of production, Keihin carburetor engineers and manufacturers made (and repeated) a HORRIBLE MISTAKE!!!
And, perhaps a forum member discovered this colossal flaw, then developed an effective countermeasure, unleashing significant "free" additional horsepower, and improving fuel economy (you mention the KLX needle uses "too much" fuel). Silly me, I thought fuel-enriching a mixture was LIKELY to process more fuel than a fuel-lean mixture might.
So . . .grind a new profile on your needle on your bench grinder, lift said needle with an O-ring, and . . . harvest this bounty of performance and economy awakened after 30 years of dormancy. Please report the before-and-after results (e.g.,
from dyno runs/drag strip timing slips/competition experience/etc.). Best wishes for your success; may you retain your dreams and enjoy their fulfillment.
I'm somehow reminded of this irrelevant anecdote: Back in the, "bad old days," when automobiles had carburetors, the legend was: This guy invented a carburetor that guaranteed 100 miles per gallon of gasoline for automobile engines of the day. Why wasn't this device ever marketed? The evil "fossil fuel" industrialists BOUGHT the patent, then sat on it (rather than producing and marketing the device) to this day, insuring all motorists would enjoy no more than the fuel efficiency of existing carburetor technology, thus using more fuel than they might with the innovative carburetor. The result from stifling the developmental carburetor? More profit for the petroleum and petro-chemical industrialists. Thus sayeth the legend!