carburator problem

OK, got her going!
Here's where I made mistakes that needed correcting: ( I had a friend who is a motor expert come help me)
First, it was racing because I connected the throttle cable a bit wrong and while it looked like I had the throttle all the way down, if you looked at it on the motor itself you could see the throttle butterfly was not closing all the way. Easy fix (with a little help from a friend and as suggested here)
Second, (again as suggested here) the two carbs are not level due to the engine angle. Although the instructions did not mention this, it appears obvious now that the floats should be adjusted differently. Can't tell you how hard I tried to get them exactly the same! This didn't cause the racing of the motor, but did make it spew a bit of fuel out of the aft carb. Raising the aft float (think toilet bowl)-lets less fuel into bowl.
She's now running like a champ and I hope to put her in the water tomorrow. A lightening storm prevented a celebratory cocktail cruise tonight.
Again, thanks for the input. I learned a lot.
~Pete

I am not familiar with the setup but it sounds like a vacuum leak, either a missing vacuum line, or a port that should be plugged, or an issue with the gasket between the carb and the intake would be likely culprits.

I don't know what to tell you except back track the steps on the rebuild. Are the throttle butterfly's closing? Is the throttle linkage hooked up correctly? I rebuilt my YH's a couple years ago and did not have the problem. Who's rebuild kit did you use. I used Daytona Parts because of their unique needle and seat. How did you set the float levels? remember they will be different fore to aft due to the angle difference on the carbs.