Finally found AT2 in pretty good shape

Sorry to hear that your post disappeared, but I can assure you it was not done by us, and our site is working just fine. Perhaps you accidently fat fingered the "Cancel" button on your phone instead of "Send" . . . We may never know what happened ???

If your bike sucked air to the tune of 5K rpm's, perhaps the seal(s) were what caused that, and not the cheap (Chinese ?) carb. It only takes a small backfire from a previous start-up attempt to blow a seal out . . . especially if you don't have the seal retainers on your bike.

You answered my questions 4 and 6, and sort of addressed question number 1, but when I ask what are the carb problems, I was talking more about the symptoms (if any), not that you switched from carb A to carb B, to carb C . . . answering question 3 would go a long ways towards answering number 1.

Don't dismiss questions 2 and 5 either ... trying a new plug is a cheap and simple test ... I wouldn't ask if I didn't think it was important. My questions help in narrowing it down to what is the real problem and the appropriate solution.

The fact that you've tried 3 carburetors on your bike, and with the same results ... "just turning over", kind of suggests it may not be a carb problem after all.

I'll address potential problems between the carb and spark plug eventually, but you're getting ahead of me. Trust me, there's a method to my madness.