The new engines are 212cc, so I don't know whether they'll be legal for kart racing or not, but they're still rated the same HP so who knows? I got one for my mini bike, so it doesn't matter to me, but for racing I'd want to check.
Word has it the stock flywheels will come apart if used ungoverned. Not a problem if used for a log splitter or compressor, thankfully. Iron cylinder liner and ball bearings on the crank. About as good as it gets for a clone of the Honda. 'Specially for a c-note.