When I said 'Maybe check the float levels?',.. it was a "clutching at straws" thing as indicated by the question marks.
My thinking was that if the float levels were set too high, and you had it jetted to give a good plug chop, then possibly?? this may result in it running a bit rich at mid range throttle settings?? But I am just making wild guesses here.
I can't really see why an "upgrade of pipes, reed valves, rear head conversion etc." would cause excess two-stroke spooge.
Maybe you changed to a 2T oil that doesn't burn as well?
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...