If it lost that much power advancing the ignition, it must be pretty close to the ragged edge to begin with. Or so my new theory went. Off came the clutch cover, the timing was retarded 2 degrees from the original setting, and I crossed my fingers. Voila! (run 075) Finally I had it. In retrospect, I hadn't accounted for the ceramic coatings on the head and piston, evidently combustion sped up a little and it needed less advance. Whatever the reason, I was just plain relieved to have found some more peak hp.