Fuel leak is either gonna break the engine or me!

Ive done a lot to this bike (mostly rubber). Rebuilt carbs and fuel petcock. Problem is if the bike sits for about 5+ hours there is a puddle of gas under it. I just got a new o ring and wave washer (+ a hole bunch more that should put chacals kids kids through college), I thought solved my problem. This morning when I sat the bike up gas poured out the air box down spout, when I tryed to start my engine seised (flooded) and a puff of smoke came out the oil pump cap bleeder hole. Removed tank ready to rip (yet again) into the carbs when I see a little drip, drip coming out of the petcock. So how long should the spring in the petcock be for proper compression of the diaphragm? (only consumable thing that wasnt replaced). Say if my needle valves are functioning properly, then should I be able to leave the petcock on prime when the bike is off? they regulate gas coming into carbs so if they are closed no gas, yeah? Floats set, but how about the little tab for the needle? Just ran cabs dry, Help!

 

In theory of your needles function it should not flood - in practice they stick a bit more than anyone would like ot admit. Mostly when going from dry to full.

If you run your barbs dry try tapping them while on primer to make sure they don't stick. If your petcock is working properly and you don't have it on prime you should not be seeing flooding/leaks. You should check and maybe revisit your rebuild.