I have a 2003 harley sportster When I Start it the over flow vent hose flows gas. What do you think the problem is? Thank you Tom

It sounds like your float level is just a bit high in the carburetor. Your bike is equipped with a vacuum operated petcock. When the engine is not running, there is no vacuum on the intake and therefore, not vacuum on the petcock. When there is no vacuum on the petcock, the fuel is turned off.

When you start the engine, vacuum is created and applied to the petcock turning on the fuel. If the float level is set too high or you have a piece of trash in the needle and seat in the carb, the float bowl will overfill and gasoline will run out of the overflow hose.

You need to take the carb off the engine, remove the float bowl, take the float and the needle out and clean out the needle and seat. Then check the float height. Now, this is an area where you need a manual. The float sets with the carb on a 15° to 20°angle. With it on this angle, you set the height to 0.413-0.453" from the carburetor flange surface to the top of the float. I usually try to set the float at the lowest fuel level setting with would be the 0.453" setting.

Good Luck
Steve