I never said the bike was backfiring. Knocking is something different. Just for the record the PO ran the bike up on a curb, knocked a hole in the engine and drained out all the oil, and then ran the bike home 6 miles. So, naturally the engine was knocking when I got it, even tho he had JB welded the hell out of the engine and filled it back up with oil. Presumably, the carbs were working just fine. I rode it around and it rode ok, minus the considerable racket from the crankcase. So I took it apart and put it in storage, where it sat until I pulled the carbs out and sold them to you. I sent you 3 excellent detailed pictures, plus the best detailed description I could give. I told you about the missing screw and the need for some cleaning/lubrication. I am sure those carbs would work for you if you wanted to invest the time in them, I never represented them as plug n play carbs and if that is what you wanted you should probably be prepared to pay more than you did. I am not some scammer or some guy looking to take advantage, and I did my best describing and showing them. I was not being deceitful in my transaction, you were the one who came all up using profanity and acting all aggressive.