Ken,
He has progressive linkage now, and what seems to be lacking is throttle response and yes, a bit of low-end bogging, even after lots of tweakign on the carbs, PVs, jetting.
As I understand it, its partly due to a velocity issue, like flushing a toilet bowl with the dual-mechanical 600s on there now. With his taller gears, the Vacuum secondary might be good; but I gotta say, even with my own Cobra, I would never go back to vacuum secondary after experiencing a finely tuned mechanical setup. Maybe its really different with dual carbs, and that is part of what I'm reading in feedback from some of you who stress vacuum secondaries on a dual-carb setup. I wish I had about 5 different carbs to test first before buying.
