Need throttle to start up bike

[7653]

FACTS:
My 2002 Suzuki GZ 250 needs to throttle to start up.
The carburetor was already recently cleaned at a service center.
The battery is new.
It was working fine before the a three-day weekend in which I did not use the bike.
(Note: when I first got the bike I had to keep throttle on at stops to keep it from stalling. After a few weeks of use I no longer had this problem but now it seems to have returned and with the additional problem of having to use throttle to start the bike up.)
I have tried adjusting the idle speed but I am not sure which way to adjust the little white knob and I don't want to turn it too much for fear I might screw it up.

DETAILS:
When I start my bike I give it max choke and have to be turning the throttle prior to pressing the starter button in order to get my bike to start. This start-up issue still persists even if I have ridden the bike for an hour and turn it off and try to start it up again. The bike has a strong gasoline smell when I try to start it up. It also sometimes has a lot of gulp gulp gulp sounds.

I also need to maintain throttle on my bike when I stop, if not the bike stalls. Sometimes after a long period of use I can remove throttle at stops for a good amount of seconds. But even then, if I leave the bike stopped for too long without throttle, it stalls.

ANY IDEAS before I give up trying to troubleshoot on my own and drive the bike to a service center?




My bike has an issue similar to:
viewtopic.php?f=7&t=5194 -- Gas contaminated with oil.
http://forum.motorcycle-usa.com/default ... 8&m=520984
-- The guy from this video said the head and exhaust header gaskets were leaking, contributing to the problem.