Okay, I’m back. I let the bike sit for several month, I guess I thought if I left it a little while it would cure itself. Didn’t happen. It will crank and run on the rear cylinder and, once in a while, fire a bit on the front cylinder.
I have disconnected the rev limiter wire, replaced the ignition black box with a known good one, rechecked the carb synchronization, set the front carb at 2 1/2 turns out on the idle screw, and replaced the front coil and plug wire with the one that came off the bike originally. It will crank on the choke and when I idle it down it is running on the rear cylinder but not on the front. When I rev it, it will start firing on the front cylinder but it won’t idle on both cylinders.
As I said before, it was running the best it’s ever ran for several months then we were out riding and stopped for about 15 minutes and when it started back up it started on one cylinder. I rode about 100 yards and it suddenly started running on both. It’s like a loose wire that suddenly makes or loses contact.
I’m running out of ideas.