So often on a hot day when I am at a red light I smell gas fumes. Most of the time, I am in traffic, and always assumed the smell was from other vehicles. But in the last week, I have been driven to work earlier, and as a result, no cars in front of me at red lights most of the time, Still smell the gas fume smell so I pulled over a few times to check things out. The smell is coming from the gas tank vent. Apparently, as our bikes heat up, the tank heats up, and generates gas vapors. Anyone notice this smell before?

 

Only after I topped off the tank. Stop filling when the pump shuts off and it leaves enough room for expansion.

 

Yep, same thing happens in cars but the smell is external. In hot sunny weather do not top off the tank. Waste of $$$ and bad for the environment to boot. Very small problem per vehicle, but with the number of vehicles out there the math isn't pretty.

Out here in LV, NV we get a lot more heat so it's more of a known problem. Still with the small tanks on bikes the tendency is to top off and the pumps seem to quit too soon.