Had a look, not much to add. It's all been done and written before many, many times, and I don't have much patience for guys who have the time to write a book on a common, simple problem but can't seem to find time for a few simple searches that would take less than half the time and effort required to tell their tale of woe. I find it suspect that the poster either has enough experience or has done enough reading to understand the operation of vacuum diaphragm systems and to do a carb rebuild that includes replacement of throttle shaft seals (no rookie task, that!) but does not own a timing light and claims to be unaware of what's making the idle spike. The Carb Guide has a fine section, written by 5twins, that covers jetting for mods, and I seem to recall writing detailed instructions on mix screw, synch, and throttle stop adjustment; whichever coauthor wrote those particular bits, it's all there and I don't have enough time left on the green side of the grass to write it again for somebody who won't spend a fraction of the time and effort I'd have to waste. If he'll push the Tech button and scroll through a few menus he'll find what he needs if he has a longer attention span than a gnat and the patience to read. Two things only to add. First: Is the original breaker point ignition still in place? If so, does the advance rod move and return freely on an unfired engine, cold and warm? Was throttle plate alignment in the venturi checked? That wouldn't be a direct cause of the idle spike, but could create other issues going forward.