Make sure the bell crank for the push cable isn't bent.
It don't take much, but if it's tweaked towards the center
of the bike, it can interfere with the eccentric adjuster for
closed throttle overtravel. And while you're at it, check to make
sure that the overtravel adjuster itself isn't out of whack. Either
condition can interfere with complete throttle closing, and you
end up not having enough adjustment at the throttle screw.
Goin by memory here, but had a similar issue with my 550, and it
turned out to be a bent bellcrank. Whatever it is, hope you get it sorted..