When i start my 2005 royal star venture it leaking fuel, coming from top of carbs under gas tank, what could be causing this problem, it does not do it all the time

pull the carbs, your pilot jets are plugged and hope your mixture screws aren't seized?

you have fuel pump run gas line direct to carbs inlet will run fine dont buy 400.00 dollar fuel pump from yamaha

Find the fuel line off the petcock and follow it to the fuel pump. The filter is between the fuel pump and petcock under the fuel tank

There's a fuel block under the tank that splits the single output from the petcock to four lines to the carburetors; a cracked or broken line or a damaged block could be the source of the leak. There's also a fuel level sensor on the underside of the tank that can leak and cause the same problem. A cheap diagnostic tool might show you the source of the leak:
mix powdered clothes detergent with water until it's a thin paste, add red (or any other bright color) food coloring to the paste, paint paste all over areas that may cause the leak (in this case, you'd paint all the fuel lines to the carburetors, and the entire underside of the tank). Drive until leaking gas is noted, check for missing colored paste.

The float is stuck open. Clean the carb.

The carb/s are flooding , you will have to check the float pin and the float, a good clean with compressed air should do the job, check too the fuel line and the fuel filter.
Hope this helps!

if & when you do get it running again, does the bike have a petcock at the gas tank? if it does, when the bike is running before you are about to park it for 2 weeks, turn the petcock off and let the bike die on its own (from fuel starvation). this will ensure there is (almost) no gas in the carb to cause any gumming. you can drain the little bit that is left with the carb bowl drain screw. then when you're ready to ride again, simply turn the petcock on, wait a few seconds for the carb bowl to fill, then hit the start button.