2 of the 5 bolts that appear to hold the cap assembly on are dummies and the holes are spaced in a way that won't let you rotate it. You can get a pop-style cap from Kewl Metal and if Ness got their venting problem fixed you can get caps from them too.
Retired USAF, IYAAYAS!
2008 V-Star 1100 Custom Bobber project
2011 Crimson XR with Forged Highway Bars / Hard Bags / Passenger Backrest, Ness parts including Smooth Layback Plate Frame/Mount / Rad 3 Mirror / deep cut grips / drivers floorboards /shifter peg / brake peg / passenger pegs. Witchdoctor black rack, Lloydz filter / timing wheel / VFC III, 7Jurock windshield, Drag Specialties seat.