This could be the problem as well. The factor limiter on the High Speed needle may not be allowing you to lean the engine quite far enough. Take the limiter off the high speed needle as well to give your self some more room to adjust it.

Four stroke glow plugs are hotter than the two stroke plugs so they don't cool down excessively during the non-firing stroke. This hotter plug will cause your two stroke timing to be too early, and will affect your low speed reliability, and make your high end look too rich as well. Go with the factory recommendation. You might also try the OS #8 or the OS A3 (my personal preference for my 46 size motors).

Brad