Thanks to all for the responses. I should have looked before I leaped. I took for granted that the previous owner's notes were correct. I have found the original box and verified that it is a 390 CFM with Vacuum Secondary by cross-checking it with the invoice from the vendor, it is NOT a Model 4160. Went on a 60+ mile jaunt today and symptoms are as stated before...clean burn above 2000 rpm, imagine that, look at the cam specs in my original post. In stop & go traffic..accel from a dead stop = sooty puff then clean till idle for 1-2 minutes. Frustrating and the bikers in my rear mirror are holding their noses!!!!!
