Ha Ha,
I plugged that on Jay Hodges' bike and the bike would stall every 20 miles or so.javascript:emoticon(':shock:')Shocked
It's the tank vent. Open your top cap and look near the hinge on the inside. There is a rubber nipple of sorts that connects the inner tank with that bottom rear access point when the cap is snapped closed. The PAIR worked like the purge canisters do on cars, saving all those evil gasoline vapors for later. Leave it open or do like me and run it down to the bottom so oversloshing won't run all over your airbox.
The other connection point under that tank is a drain for accidental overfilling of the tank. Run that line down, too.
Marc/Atlanta