rebuild carbs

Hello! I'm rebuilding an 82 Yamaha virago 750, I rebuilt/cleaned the carbs bought a new starter, oil change and clean gas. I got it running! But gas is leaking out of the front carburetor when I turn it off (at the front boot). It doesn't leak when it's running. Any ideas to the cause? Thanks in...

I just picked up a 82 CB900C, Carbs are hangin off of it and I know that someone had them apart, I want to go over them with a fine tooth comb and make sure they are together the right way, but I would really like a detailed manual to follow. Anyone with suggestions before I start pulling it...