CB1100 Idle speed instability problem

[dave]

Thanks for all of your suggestions guys. I haven't looked at the service manual concerning this topic yet, but to my knowledge there is only one vent tube coming out the bottom of my tank. The fact that I can blow air freely through this tube makes me believe this hose is not blocked. Also, I am 100% sure that this tube is the correct tube that attaches to the bottom of the tank, but what I am not 100% sure of is it is not being pinched when I lower and attach the tank. Max has some good ideas, thank you Max, but what I am going to do tonight is disconnect this tube from the bottom of the tank and then go for a ride. If the vacuum issue persists, then I know this hose has nothing to do with it, and the problem is most-likely the fuel cap. I'll post the results of my experiment tomorrow.