Damn. For all the gas I have lost through my atmospherically vented fuel cap in the last 6 months, I prolly coulda enjoyed a free Big Mac for lunch today. Thing is, after the bike is sitting in hot sun, when a carb overflow: ie: also known as a carburetor bowl vent line becomes pressurized due to being hooked up to another vent line: ie tank vent, and eventually pressures build on either side and the vapor needs to vent somewhere. Question is, where is it going to vent now? Might make for some troublesome hot starts after its been sitting. If you're that worried about saving gas, you should possibly consider a moped. If the smell of gas is that detrimental, well, I dont think there is any good advice there. Usually I only smell like gas after I'm working on my carb.