success! it was the carbs, or the air filter. I rebuilt the carbs, (the o-rings were very flat and cracked on closer examination) and changed out the diaphrams. good cleaning (with pine sole). I changed the air filter. not sure it needed it or not, but I figured it couldn't hurt. Anyway, it runs like a scalded dog! I just got back for a long(ish) ride in the country, feels good to be back on the road!