Well, I drove it a couple times last Sunday and it ran well. I parked it for the night and got it out on Monday to ride. I started it with the choke as I always do and it seemed to idle the same as usual. I got out to the highway and pulled out into traffic. As I tried to accelerate up to speed, it would stop between 2 & 4k and hesitate. It also seemed to want to die unless I had the throttle above idle. I messed with the screws on the sides of the carbs and tried to readjust the cam chain tensioner. Now it'll accelerate, albeit much slower than I think it should, and even under cruising throttle at the neighborhood speeds I was riding, I'll get a hesitation rather regularly, perhaps once every couple of seconds.
I don't know if this symptom is related, but it still seems to rattle at idle. I've been assuming the problem is un-synchronized carbs. I did notice that with the oil fill screw out, the noise is much easier to hear.
I'm going to try an oil change this week and see if that helps. While I've got the oil drained, I may try to take the oil pan off and peek up underneath. The only thing I can think of doing differently is adding Seafoam to the gas and oil but it was more than a couple rides before the symptoms appeared.
