I have read a lot on TT but can't find an instance like mine. I recently put new rings on the bike, long story, but I decided to check everything while I was in there and everything was within spec. After I got it all together it ran great then the next day it was like I had a fouled plug or it was out of time, popping and backfiring with a bad bog , idles fine though. After an hour or two it runs great again. A week later and it is screwed up again, this has gone on for quite a while back and forth and I have checked and rechecked the timing gone through several plugs, cleaned carburetor a couple of times and still this stupid problem. This morning I went to go riding and it didn't work, after cleaning the carb one more time it worked, until I got there and it acted up again. Any help would be appreciated and sorry for the long post.