If you read Paul's post in that thread, he sometimes has a fuel smell after parking his scoot and believes it's just pressure venting from the tank. I'd just watch for a fuel leak to be sure.
After I got my 650 in '08, I too noticed that in my bike but after I tightened the hoses on the tank, it pretty went away. And I live in SE Arizona, where its very HOT and DRY in the summer. Even a 100+ degrees in my garage, and an empty tank, the venting is minimal, especially after I tightened the hoses. During this time of year you should not have much (if any) 'venting', though. Anyways, as a start, you might wish to check the tightness of all your fuel tank and line hose clamps.
Vapor emissions, including those resulting from leaks of liquid fuel, can be classified into five categories: diurnal, hot soak, running loss, resting loss, and refueling loss.
* Hot-soak emissions occur after vehicle operation has been terminated.
* Running-loss emissions occur as the tank is heated during vehicular operation.
* Resting-loss emissions include escape of fuel vapor by means of permeation of nonmetallic components of the fuel system while the vehicle engine is not operating.
* Refueling emissions consist of the fuel vapor displaced from the tank headspace by the new liquid fuel being pumped into the tank.
If the tank is supposed to be sealed (up to a predetermined pressure), and the ambient temps are cool to cold, then vapor pressure should be low, and no 'venting' of fuel tank pressure should occur. If 'venting' does occur, then that implies there is some sort of 'valve' - if the valve is malfunctioning, well, that could be the source of vented fumes, especially in cooler weather when pressures are lower.
Anyways, I found this regarding motorcycle emissions....Good information to know:
http://www.sportrider.com/features/146_ ... index.html