Smoggyboy, I run mine with an OS 'F' plug, GX 10% and its also inverted. Run a few tanks through it on the bench before installing it, it is so much easier to adjust the needles this way. Also run it very rich for the first 2 tanks, and revs at 4000 RPM max, keep the glow driver on if needed. My engine has got better the more I run it, at first I thought it had poor compression, but it has improved with running.

p.sp check the valve clearences as well, mine were a bit sloppy from the box.