I should update this post, since I started it. Last month I rode down to Westfir, OR which is a bit east of Eugene, for an Airheads tech day. I was in luck as the Oregon Airmarshall Gary Newby and friends were just hanging out, not wrenching, so I explained my problem, demonstrated the misfire, and put them to work. They completely ignored me talking about the timing marks wiggling and proceeded to check my spark plugs. The one on the right was pretty dark, as it always has been. I thought it had something to do with the breather oil but they said no.
...here's where you all get free shots at me for withholding pertinent information. I'm sorry.
They pulled off the hoses between the carbs and air box to make sure both slides were operating properly, which I though was pretty clever. They then started zeroing in on the right side carb. They dropped the needle to the next lower (leaner) setting, which helped some. They put in a smaller main jet, which I thought helped some, and finally put in a much smaller than stock needle jet (I stupidly did not record the size.), which cured the problem. Or the symptom, to be precise. I rode home like that and the bike had trouble pulling my stupid speeds over a small pass, so over the next week I reinstalled the stock main jet, and it still ran well. I put the carb needle back in the correct position, and it still ran well. So it's running well with a needle jet at least one size too small.
Obviously something is wrong with that carburetor. I've speculated that maybe the threads that the jet holder screws into are stripped, or the o-ring is the wrong size, or something, such that fuel is bypassing the needle jet, and I'm compensating by having a smaller needle jet. I tend to put things off, as the bike is running well and I'm riding it to work a couple times a week, but I WILL take that sucker apart again to search for why it needs so small a needle jet.
Besides, I need to return the jet.
I tested it a few weeks ago on a long straight road and it will still go up to 7,250 rpms in top gear with no problems.
