Hello. I just picked up a Grubee gt2 frame from a company called Piston Bikes. The frame looks the same. but the fuel tank filler is a push and turn like on all the kit tanks, and it is really hard to open and close. but the one on the grubee site and other sites, look like a spin on type. also my fuel petcock from my grubee 4g engine kit will not thread in. Has anyone ordered from this company before? are they good? did I buy a KNOCK OFF? Or am I doing something wrong. Any help would be great.