OK I cleaned the bejeebus out of the carbs (completely disassembled and soaked all the parts in Simple Green overnight). When I finished putting the bike back together it started on the 3rd kick and ran like a champ.
A couple days later went out to the dunes and still basically the same problem. Would not kick start at all first thing in the morning and had to get a tow to bump start it. The rest of the day it started on the first kick but didn't run right. First it was bogging at WOT, then it ran OK for a while, then the last hour or so it bogged at all throttle positions.
I pulled the plugs and they are both dry as a bone. Next up I'm checking the reeds, compression, and spark.