Worth noting that Honda GX series is on a different level to the clones when it comes to durability. At least in my experience. I worked a lot with the dual Gx160 pro karts back when they were a thing.
While a “genuine” Gx flywheel has shown itself to be up to the sustained RPM of racing, the clones have shown this to not always be the case.
I have a split-in-half coil (390clone) knocking around here that got destroyed by a magnet that went into orbit 
So I am moving forward with a box stock clone on a CRG chassis for my son to get his karting feet wet. However I am discovering that even though metric hardware is common on sprint karts something happens when you put a 4 stroke with a 35 chain, a lot of the hardware becomes American. Whats up with that?
Also, I acquired a Black Rhino motor mount without butterfly clamps. It seems to be primarily used in oval racing but I am not finding much information and zero for replacement clamps. Does anyone have insight?