Let me correct my last statement. It needs more initial advance. Don't know the amount of advance in the Dyna curves. I'd trade a little off of the curve for the same amount added initially. We aren't trying to be smooth for the street. The advance curve just gets the bike from idle to 4k on the starting line. We need to do that in the least amount of time that we can. Not looking to increase the total advance, but you really will run quicker with more initial advance. We have about one second to whack the throttle from idle to load the motor against the brake. If you whack the throttle too early (before the christmas tree starts down, you run the risk of increased oil temperatures that may/will slow your run down) The stall speed of the converter should be approached just as you release the rear brake. With the throttle response that I'm hearing, I'm betting that you are leaving around 300 rpm below where it could be launching. That will slow the bike, but not make it less consistent. I'm just trying to get everything out of what you've got.
What did the tach show when you tried loading the back brake? My guess would be in the 3,500 to 3,700 range? (Motor won't pull to stall speed of the converter with current horsepower level) Was the transition off of idle to midrange a smooth one? Don't think that you'll find much with the carb sync'ing. A little detergent in the gas won't hurt. Fresh plugs at the track will help. Does the Dyna box not give enough spark energy to keep the plugs clean? Plug gaps are ? I like to keep them a little small .025 ish on my bikes.
With a 10.5 to 1 ratio, you could get away with less octane. Won't make much difference on the time slips, but might affect your wallet a little less. (not counting the VP oxygenated gas that some tracks offer)
Rear brake holding well is a major engineering success! Minor tweaks from here on out! Sam, what's your reflections on seeing it running? Anticipation increasing?
JW