Kawasaki has not changed the design of these for over 10 years now, as I have had the same problem with the last 4 bikes ZRX's x2 ZZR1200 & ZX14R same fuel cap, same problem. My suggestion on this replace the fuel cap with an after market product!
Neil
Penske 8983 Ohlins 20mm supersport valving Racetech 1.1 N/mm springs Powerbronze carbon hugger Akra headers Akrapovic titanium mufflers Muzzy sliders Cox rad guard Vortex rearsets Throttlemeister bar ends Zero Gravity DB screen A-Tech front carbon fender Hel SS braided brake lines Clever Wolf carbon tank guard DNA air filter MDI carbon ram tube covers Brock's/ Ohlins steering damper Driven fuel cap Ventura rack Driven D-Axis grips PIAA headlights Muzzy fender eliminator Bestem carbon battery cover Custom ECU tune.