I was previously running a generic, eBay special gas cap. This was an item I admittedly cut corners on. It did the job, but I felt compelled to replace it because I wasn’t overly confident regarding its ventilation or seal. I also wasn’t a huge fan of the cap, which simply threads on.
Old (still significantly lighter than stock):
I picked up an Accossato quick-turn gas cap from HardRacing.
The Accossato cap looks strikingly similar to the Harris units from the UK (which are no longer imported to the States)… I wouldn’t be surprised if they’re the same. GREAT gas cap though, the quick-turn system is easy and convenient to use. There’s also proper ventilation:
The vent hose routes into this hole on the gas tank:
It retails for $135 so there are cheaper alternatives, but I personally think it’s the best design-wise. The locking mechanism’s audible and tactile click is a good touch, as well.
Here’s a video of it in action (and a brief walk-around for the hell of it)… EASY.