I found that my O-ring on my Himoto Syclone wasn't sealing the gas tank properly...after replacing it with one from my universal set (whole bunch of O-rings) I hear a pop when I open the tank and have to push it down a bit to close it...also put some aviation Gasket Maker on top of the plastic piece cuz that may be leaking too...can't check if it leaks right now (cannot start my car therefore not putting fuel in it) but I'll keep ya posted