no it wasnt carb icing, it was a connector gradually coming loose! and whats really annoying is klaus told me about it months ago! GRRRRRRR!!
it was the wire between the CDI and ignition switch. i checked the wire and switch and both were fine, but it was the connector on the end that was bad, the female had no grip on the spade in the CDI! vibration of the engine made it move around and made the engine stutter and cough. a squeeze with pliers to tighten it up again and the bike now runs better than it ever has, with no 3000RPM "burp".
so dont just check the wires, look at the connectors on the end, too!