Yes, I have two cases. One is a replacement case where the dealer stamped the number on the engine. The other one is a factory stamped engine number and I have many of the engine parts that came inside. It was left outside for years when I bought it but most of the parts can be cleaned and...
I just finished restoring a 1971 CB750 and had sputtering when I gave it full throttle. I removed the air cleaner to troubleshoot and the problem did not occur. So that told me it was running too rich at full throttle. At full throttle, the main jet is the one to change, so I went from a 120...
I would suspect it is running too lean if it sputters when you back off the throttle. One way to help diagnose it is to remove the air cleaner and take it for a ride. If the problem gets worse or stays about the same, it is too lean.