1971 Honda cb 350 carb?

My Honda won't start. It was just tuned by a honda shop and was running great. I painted the bike and took the tank off to paint, drained the gas, then put it back together. I put the gas back in, rode it that night and it ran fine. The next day I went to ride it again and it wouldn't stay running at idle. Had very little power when I was riding it and was stop and go feeling. it would have spurts of power then go away. I'm positive it's the carb as it won't even start now. I think the gas might have something to do with it. The gas cans I put it in may have been dirty and I drained that gas and put in fresh gas but it didn't help. I also took off the carb, being careful not to tilt itor turn it upside down.I sprayed it down with carb cleaner and put it back on and it still didn't help. I need idea's. I know very little about carbs and any help is appreciated