If you pull off the carb drain and the gas is ON then it will just keep draining till the tank is emty LOL, if the gas was off there is a fair amount in the bowl and the hose leading from the tank to the carb, it may seem like it takes forever but it's a small hose.. As far as gas in the air box when the fuel is shut off then it came from what was in the carb and abit from the hose to the carb. Do you have a snorkle on the bike , The vacume effect from the snorkle going through the air when trailering will pull the gas into the airbox. If you have a snorkle just cap it when trailering . Hope this helps