2007 ltz 250 quad carberator problems

I have a Suzuki 2007 ltz 250 quad, My first problem was fuel would flow out of the drain line from the botttom of the carberator when the drain screw was closed when the quad was running, it ran bad, I figure the float was stuck so I took the float bowl off and cleaned the bowl and lower part of carb with carb cleaner, I put it back together it works o/k. I took the quad to the dunes at sand lake Or, it wored o/k, I notices that a small amount of fuel at the end of the fuel drain line, the drain screw is tight, when I cleaned the carberator bowl I noticed a small tube that csme up straight out of the bottom about and inch, it would by pass the drain screw and allow fuel to drain. Is this a commom thing with this set up that fuel will drain out when going up and down hills.