I have a ct70 clone with an 87cc engine from REDCAT Motors. Its a great bike, im about to upgrade to a 125cc zongshen.
I Had problems registering mine as well. First i was allowed to register it. Then they revoked my title saying my bike wasnt EPA certified. I contacted the EPA, and they said my bike was EPA certified, but because my bike had no EPA stickers they couldnt help me.
So i had 2 routes i could go. I could swap all the new parts onto a Pre-1975 frame. I live in Alabama and anything older than 1975 only requires a bill of sale, and no emissions requirements. The other way, that was real easy. I took a seat off a 1991 ct70, which had the EPA stickers underneath, mounted the seat on my bike, showed the DMV, and got my title. They had no idea what they were looking at. If they ask to see it now ill tell them i got a new seat and new engine!
Neil