For 15 years I've had starting problems on my 1995 Skorpion Tour. If I left it more than about 10 days it wouldn't start and the engine would simply churn over and over and over....... so much so that it's credit to the starter motor that it's still working. I've tried everything, new plugs, carb strips too many to mention etc. Cutting a very long story short, this winter I laid the bike up for the first time and winterised it, draining the carbs, a bit of oil in the plug holes etc. When I came to start it after five months, full of dread, I opened the fuel tap ( I've got it on gravity feed, no fuel pump) , operated the choke, hit the starter and it started, first push. Since then I've drained the carb after every ride and when I come to start it again it goes, first push. So what happens to fuel standing in the carb float bowl that doesn't happen to it in the tank? I don't know, all I can say is that draining the carb works for me.
Riding it is much more fun than polishing it.