Consider this: If you grab a handful of throttle and it falls flat and then picks up, the bottom end is lean. If you grab the throttle and it gargles then goes, its too fat or rich. If its just sluggish with none of the above look at more timing. If its starving for air it will show a tendency to be rich on the low. Get a Mikuni, its adjustable on low/ mid/ and hi speed. With a little work you can dial it in with a adjustable low, a needle for the mid and a jet for the Hi end. Jetting, do with a plug reading at hi throttle, beware of who you listen to. :shrug:Walt