I have a 1974 CB360, the original carbs diaphragms were shot, so I invested in some Mikunis. After doing a little more research I wish I would have went with some 30 VMs. It seems as if it is running way to lean right now. It has a 190 main jet, and a 35 pilot jet. If it is backfiring into the air filter does that indicate lean? It also seems to take a little bit to idle down after you rev it up. I took the filters off and used my friends and I hands to restrict some air and it seem to run pretty good. It idles but if you give it too much throttle it dies. I found one guy with the same carbs and bike and he switch to a 150 main, and a 30 pilot. So I went out and found the 150 mains and when I put them in it seem to run way way lean.